;  '     '        ,-"" 

i  m '  '/';     -   :. 


• 


THE  LIBRARY 

OF 

THE  UNIVERSITY 

OF  CALIFORNIA 

DAVIS 


m 


m 

m 

•••••• 


I 


-  -    - 

. 

- . . . 


I 


£^>       , 

. 


HANDBOOK 


OF 


PLANT    DISSECTION 


BY 
J.  C.  ARTHUR,  M.Sc., 

Botanist  to  the  New  York  Agricultural  Experiment-Station, 

CHARLES  R.  BARNES,  M.A., 

Professor  of  Botany  in   Purdue    University, 
AND 

JOHN  M.  COULTER,  PH.D., 

Professor  of  Botany  in  Wabash  College \ 

EDITORS  OF  THE 
BOTANICAL  GAZETTE. 


NEW  YORK 

HENRY  HOLT  AND  COMPANY 

1886 

I  iRR  ARY 


COPYRIGHT,  1886, 

BY 
HENRY  HOLT  &  CO. 


Press  of  W.  L.   Mershon  &  Co. 
Rahway,  N  .  J, 


PREFACE. 

A  rich  harvest  of  laboratory  manuals  has  resulted  to 
zoology  from  the  publication  of  Huxley  and  Martin's  Ele- 
mentary Biology  ten  years  ago.  Although  that  work 
embraced  both  animals  and  plants  with  over  half  the 
examples  from  the  latter,  it  has  given  rise  to  no  similar  aid 
to  botanical  study  till  the  past  year.  The  increasing 
laboratory  facilities  in  this  country  seem  to  warrant  the 
expectation  that  an  elementary  manual  like  the  present 
work  will  now  be  found  in  many  instances  to  afford  wel- 
come assistance  to  both  teacher  and  pupil. 

In  1882  one  of  the  authors  of  this  book  drew  up  an  out- 
line of  work  for  a  few  plants,  which  was  used  in  the  Summer 
School  of  Science  of  the  University  of  Minnesota.  Not 
long  afterward  the  preparation  of  the  present  hand-book 
was  actively  undertaken  by  the  three  authors  conjointly, 
and  has  since  been  gradually  perfected  and  tested  by 
repeated  use  with  classes  and  individual  students. 

Although  the  present  work  is  based  upon  Huxley  and 
Martin's  in  form  and  mode  of  treatment  for  the  laboratory 
part,  it  differs  in  excluding  all  matters  of  physiology  so  far 
as  possible,  as  the  present  demands  of  vegetable  physiology 
will  hardly  permit  harmonious  treatment  along  with  a  course 
of  dissection. 

In  drawing  up  the  outlines  of  work  the  aim  has  been  to 
direct  the  student  in  a  very  careful  and  systematic  exam- 
ination of  a  few  examples,  so  that  while  he  is  securing  a 
knowledge  of  the  main  features  of  plant  anatomy,  he  will 


iV  PREFACE. 

at  the  same  time  acquire  the  habit  of  close  and  critical 
observation,  which  is  indispensable  to  the  successful  pros- 
ecution of  natural  history  studies.  To  this  end  the  direc- 
tions for  finding  the  different  parts  have  been  made  as 
explicit  as  possible,  and  at  the  same  time  as  little  informa- 
tion given  about  them  as  seemed7  advisable  ;  for  the 
student  having  found  the  part  is  expected  to  examine  it 
thoroughly  until  he  has  found  out  all  that  may  be  readily 
seen.  This  rule  has  been  modified  according  to  the  diffi- 
culties to  be  overcome,  and  in  extreme  cases  full  information 
has  been  provided,  which  the  student  is  only  expected  to 
verify.  On  the  other  hand,  it  will  repeatedly  happen  that 
more  may  be  learned  by  an  acute  observer  than  there 
is  any  hint  of  in  the  outlines,  as  the  work,  though 
deemed  sufficiently  exhaustive  for  the  student,  is  far  from 
being  so  for  the  specialist. 

In  the  use  of  such  outlines  as  these  there  is  always 
danger  that  the  student  will  slight  the  study  of  those  parts 
which  he  is  expected  to  work  out  for  himself  and  only 
attempt  to  verify  the  portions  where  the  information  is 
fuller.  If  it  be  found  that  too  great  dependence  is  being 
placed  on  the  manual  it  will  be  advisable  to  substitute 
plants  allied  to  those  named,  thus  withdrawing  all  exact 
information  ;  the  laboratory  directions  will  still  serve  as  a 
guide  to  the  order  and  methods  of  examination. 

It  has  been  no  part  of  the  present  aim  to  provide  a  key 
to  the  nomenclature  of  plant  anatomy.  When  tech- 
nical terms  are  used,  as  indeed  is  necessarily  very  frequent, 
they  have  usually  been  preceded  by  descriptive  definitions, 
either  direct  or  implied.  A  glossary  is  added  to  further 
assist  the  student,  so  that  he  may  find  as  little  difficulty  with 
the  names  as  possible,  and  devote  himself  chiefly  to  the 
objects  themselves.  On  this  account,  and  on  account  of  the 
progressive  series  of  forms  which  have  been  chosen,  it  is 


PREFACE.  V 

hoped  that  the  work  will  be  found  suitable  not  only  for 
classes  pursuing  a  regular  course  of  lectures,  but  also  for 
those  who  have  never  before  studied  botany,  and  for 
home  use  away  from  the  assistance  of  a  teacher. 

The  required  apparatus,  reagents  and  materials  have  been 
reduced  to  a  minimum,  difficult  manipulations  (except  the 
cutting  of  sufficiently  thin  sections)  have,  to  a  large  extent, 
been  excluded,  and  the  minute  anatomy  has  been  kept 
within  the  limits  of  the  average  microscope  used  in  the 
botanical  laboratories  of  this  country,  in  short,  the  attempt 
has  been  to  provide  a  guide  to  the  study  of  a  few  common 
plants  in  which  simple  appliances,  coupled  with  persever- 
ance and  keen  observation  on  the  part  of  the  learner,  are 
the  only  essentials. 

Under  "gross  anatomy  "  the  plant  is  first  examined  with 
the  aid  only  of  a  hand  lens,  and  then  passing  to  "  minute 
anatomy,"  every  part  is  subjected  to  the  compound  micro- 
scope. A  student's  success  in  the  latter  may  often  be 
gauged  by  his  ability  to  discover  all  there  is  to  be  seen 
under  the  former. 

The  laboratory  work  for  each  plant  is  preceded  by  direc- 
tions for  the  preliminary  finding  and  preparation  of  mate- 
rial. It  is  followed  by  annotations  which  serve  a  number 
of  purposes  :  (i)  to  explain  obscure  matters,  (2)  to  give 
additional  information  which  for  want  of  higher  powers, 
special  reagents  or  proper  materials,  the  student  is  unable 
in  the  usual  limited  time  to  secure  for  himself,  but  which  is 
essential  to  fully  round  out  the  subject,  more  especially, 
however,  (3)  to  give  some  insight  into  the  course  of  develop- 
ment from  the  lower  to  the  higher  forms  which  will  serve  as 
a  thread  on  which  the  most  important  facts  ascertained  in 
the  laboratory  work  may  be  strung,  and  not  the  least  (4) 
to  direct  the  student  to  sources  of  additional  information  by 
means  of  which  he  may  pursue  his  inquiries  as  far  as  he 


vi  PREFACE. 

may  choose.     The  annotations  are  necessarily  fragmentary 
and   disconnected,  and   the    references  to   literature  only 
sufficient  to  start  the  student  in  his  researches. 
January,  1886.  THE  AUTHORS. 


CONTENTS. 


ILLUSTRATIONS  IN  GROSS  ANATOMY. 

Explanation  of  Plate  I,  * 

ILLUSTRATIONS  IN  MINUTE  ANATOMY. 

Explanation  of  Plate  II,  xiii 

INTRODUCTION. 

Instruments,    -  I 

Reagents,               -  4 

Care  and  use  of  microscope  and  lens,  6 
Section  cutting,     - 

Mounting,        -                                                   -  u 
Applying  reagents,                                    -                         -       !3 

Care  and  use  of  material.        -  15 
Drawing,  -                                                                -            -       16 

Books  of  reference,      -  19 

GREEN  SLIME  (Protococcusviridis}. 

Preliminary,     -  22 

Laboratory  work,  23 

Annotations,   -                                                                -  25 

DARK  GREEN  SCUM  (Oscillaria  tenuis). 

Preliminary,  -  -       28 

Laboratory  work,         -                                      -  29 

Annotations,                                               -  31 

COMMON  POND  SCUM  (Spirogyra  quinina). 

Preliminary,     -  32 
Laboratory  work,                                                                   -       34 

Annotations,   *           *  39 


vm  CONTENTS. 

WHITE  RUST  (Cyst opus  candidus). 

Preliminary,  „       ^r 

Laboratory  work,         -  .  -            -            44 

Annotations,  _            _            -      48 


LILAC  MILDEW  (Microsphara  Friesit). 

Preliminary,     -  -            -            52 

Laboratory  work,  .            _            -       52 

Annotations,   -  -            -l          55 

COMMON  LIVERWORT  (Marchantia  polymorpha). 

Preliminary,  _            _            -       c8 

Laboratory  work,  _            .            ^ 

Annotations,  -            .            -       77 

MOSS  (Atrt'chum  undulatuni). 

Preliminary,     -  -            -            84 

Laboratory  work,  _            -       86 

Annotations,    -  yj 

MAIDEN-HAIR  FERN  Adiantum  pedatum). 

Preliminary,   -  Io^ 

Laboratory  work,  .     Io^ 

Annotations,    -  -                       124 

SCOTCH  PINE  (Pinus  sylvestrts). 

Preliminary,  _            -     130 

Laboratory  work,        -  -          132 

Annotations,         -  -            -            -            -     161 


FIELD  OATS  (Avena  sativa). 

Preliminary,     -  ij2 

Laboratory  work,  ^     J72 

Annotations,   -  2 


CONTENTS.  ix 

TRILLIUM  {Trillium  recurvatum). 

Preliminary,  -     197 

Laboratory  work,  198 

Annotations,  -     215 


SHEPHERD'S  PURSE  (Capsella  Bursa-pastoris). 

Preliminary,     -  222 

Laboratory  work,  -     223 

Annotations,  -  236 


GLOSSARY,      -  -    243 

INDEX,       -  -  251 


X   * 

EXPLANATION  OF  PLATE  I. 

ILLUSTRATIONS    IN    GROSS  ANATOMY. 

Fig.  i.  Diagram  of  an  open  flower  of  Trillium  showing  the 
number  and  relative  position  of  the  parts  :  s  sepals,  p  petals,  st 
stamens  in  two  whorls,  c  carpels  each  bearing  two  ovules. — Drawn 
with  pen. 

Fig.  2.  Diagrammatic  drawing  of  Marchantia  to  show  the  mode 
of  branching,  somewhat  enlarged.  As  one  branch  of  each  new 
dichotomy  soon  distances  the  other,  it  produces  the  appearance  of  a 
main  axis  with  right  and  left  branches  :  an  the  extension  into 
an  antheridial  branch,  ar  extension  into  an  archegonial  branch,  y 
recent  dichotomy,  o  o'  older  dichotomy  in  which  o'  is  already  per- 
ceptibly longer,  c  cupules  which  arise  at  the  growing  end  of  the 
midrib  and  are  left  upon  its  upper  surface  as  the  stem  advances. — 
Drawn  with  pencil. 

Fig.  3.  Flower  of  radish,  greatly  enlarged  and  modified  by  the 
growth  of  Cystopus  within  it,  natural  size.  The  change  induced 
by  Cystopus  is  variable,  sometimes  single  flowers  are  enlarged,  as 
in  this  case,  sometimes  the  whole  cluster  of  flowers  is  changed 
when  the  individual  flowers  remain  smaller.  This  example  is 
larger  than  the  average  size. — Drawn  with  pencil. 

Fig.  4.  A  small  fruiting  plant  of  Atrichum,  X  2 :  the  stem  bears 
scale  leaves  below  and  foliage  leaves  above,  the  base  is  clothed 
with  rhizoids  that  simulate  roots,  st  seta,  sp  capsule  sur- 
mounted by  the  closely  fitting  calyptra.  The  distance  the  beak 
extends  into  the  calyptra  is  indicated.— Outline  drawing  with  pen. 

Fig.  5.  Flowering  head  from  a  vigorous  male  plant  of  Atrichum, 
X  2  :  the  difference  between  the  perichaetial  and  foliage  leaves  is 
well  shown. — Drawn  with  pen. 

Fig.  6.  Pod  (seed  vessel)  of  Capsella,  X  2.— Drawn  with  pen. 


PLATE  I. — Gross  Anatomy. 


PLATE  II.  -Minute  Anatomy. 


EXPLANATION  OF  PLATE  II. 

11.1  ISTRATIONS   IN    MINUTE   ANATOMY. 

Fig.  7.  One  of  the  pair  of  fibro-vascular  bundles  in  a  leaf  of 
Pinus,  x  400  :/  phloem,  .r  xylem,  sv  group  of  spiral  vessels  (in 
other  bundles  they  are  often  more  scattered),  ;//  ;//  rows  of  paren- 
chyma cells  forming  medullary  rays  containing  starch  in  the  xylem 
and  protoplasmic  substances  in  the  phloem,  r  resin  duct,  f  f 
fibrous  tissue  with  thick  walls,  small  cavities  and  prominent  middle 
lamellae,/'  fibrous  cell  with  lateral  pjt,/^  thin-walled  parenchyma, 
//•  /;•'  parenchymatous  tracheides  with  bordered  pits,  tr'  face  view 
of  the  pits  on  an  end  wall.  The  other  bundle  of  the  same  leaf  was 
at  the  left  side  of  this  one. — Drawn  with  pen. 

Fig.  8.  Diagrammatic  drawing  of  a  vertical  section  of  leaf  of 
Capsella  showing  a  sorus  of  Cystopus,  X  ico  :  ue  upper  epidermis, 
le  lower  epidermis,/  palisade  parenchyma,  s  spongy  parenchyma, 
fb  small  fibro-vascular  bundle,  h  hyphae  passing  between  the  pali- 
sade cells  and  terminating  in  c  the  conidiophores  which  bear  the 
chains  of  conidia  c' .  The  epidermis  is  raised,  but  not  yet  ruptured, 
above  the  sorus. — Drawn  with  pen. 

Fig.  9.  Cells  of  Protococcus  after  treatment  with  chlor-iodide 
of  zinc,  X  430  :  w  the  thick  cell  wall,  c  large  chlorophyll  bodies, 
;/  nucleus  with  central  nucleolus. — Drawn  with  pencil. 

Fig.  10.  Diagrammatic  drawing  of  a  transverse  section  through 
the  ovary  of  Trillium  showing  one  entire  carpel,  which  is  shaded, 
and  a  portion  of  the  other  two,  X  12:  ww  the  pair  of  wings,//  the 
three  placentas  meeting  in  the  center  of  the  ovary,  x  xylem  and  p 
phloem  of  the  fibro-vascular  bundles  of  which  each  carpel  has  one 
between  the  wings  and  one  in  each  placenta,  o  ovule  which  re- 
ceives a  branch  from  the  fibro-vascular  bundle  of  the  placenta  to 
which  it  is  attached. — Drawn  with  pencil. 

Fig.  ii.  Diagram  to  illustrate  the  theoretical  carpellary  struc- 
ture of  Trillium,  representing  a  single  carpel  in  transverse  section 
as  in  fig.  10,  and  with  the  same  lettering. — Drawn  with  pen. 


INTRODUCTION. 


I.  INSTRUMENTS,  ETC.  . 

Following  is  a  list  of  the  instruments  and  appliances 
necessary  and  desirable  for  use  with  this  manual. 
Those  printed  in  italics  are  necessary  ;  the  remainder 
are  desirable  but  can  be  dispensed  with. 

GROSS  ANATOMY.  MINUTE   ANATOMY. 


Hand  lens, 
Dissecting  needles, 
Razor  or  scalpel, 
Glass  slips  (3), 
Cover  glasses  (6), 
Drawing  materials, 
Holder  for  lens, 
Dissecting  microscope, 
Fine  forceps, 
Fine  scissors, 
Camel's-hair  brush, 
Metric  rule. 


Compound  microscope, 
Razor  or  scalpel, 
Glass  slips  (12), 
Cover  glasses  (24), 
Fine  forceps, 
Dissecting  needles, 
Drawing  materials, 
Blotting  or  filter  paper, 
Camel's-hair  brushes, 
Fine  scissors, 
Watch  glasses, 


Dropping  tube. 

The  hand  lens  should  have  a  magnifying  power  of 
eight  to  fifteen  diameters;  one  of  ten  or  twelve  diam- 
eters is  the  best.  Such  a  glass  costs  from  50  cents  to 
$5.00,  according  to  quality  and  mounting.  One  costing 
$1.00  will  be  found  sufficiently  good. 

A  holder  for  the  lens  may  be  constructed  as  follows 
and  answers  every  purpose  of  a  dissecting  microscope  : 


2  INTRODUCTION. 

Take  a  block  of  wood  about  10  cm.  long  and  6  cm. 
wide.  Fix  upright  in  the  middle  of  the  block  about 
2  cm.  from  one  end  a  bit  of  metal  rod  of  3  to  4  mm. 
diameter  and  6  to  8  cm.  high.  Bore  a  hole  a  little  to 
one  side  of  the  center  of  a  smooth  cork  so  that  it  will 
slide  smoothly  on  this  rod.  Bore  another  hole  at  right 
angles  to  the  first  through  which  pass  a  wire  of  7  to  8 
cm.  length.  The  free  end  of  this  wire  may  be  bent  into 
a  loop  or  circle  as  maybe  desired  to  hold  the  lens.1  The 
lens  may  be  focused  by  sliding  the  cork  up  or  down. 
Cheap  loupe  holders  are  also  to  be  had  of  dealers  in 
optical  goods. 

The  mounted  needles  can.  be  better  made  than  bought. 
Take  two  number  8  "  sharps,"  break  off  about  one-third 
of  the  needle  from  the  blunt  end  and  grasping  the  remain- 
der firmly  with  a  pair  of  pliers,  push  the  blunt  end  into 
a  pine  pen-holder  or  any  suitable  piece  of  soft  wood 
till  firm.  The  points  of  the  needles  should  be  kept 
sharp. 

The  razor  should  be  of  the  best  quality  of  steel 
without  any  stamped  lettering  or  even  etching  on  the 
blade,  which  should  be  at  least  2  cm.  wide.  The 
best  shape  for  the  blade  is  to  be  ground  flat  on  the 
under  side  (when  held  in  the  right  hand  with  the  edge 
toward  one)  and  hollow  on  the  upper.  Next  to  this 
shape  the  "hollow  ground  "  razor  is  best,  provided  the 
thin  part  of  the  blade  is  at  least  12  mm.  wide  and  not 
so  thin  as  to  be  easily  bent.  "  Extra  hollow  ground  " 
razors  have  the  blade  too  thin. 

Glass  slips  with  ground  edges  may  be  purchased  of 
any  dealer  in  microscopical  supplies  or  they  maybe  cut 
1  Modified  from  Kingsley,  The  Naturalist's  Assistant,  p.  83. 


INTRODUCTION.  3 

from  clear  window  glass,  or  better  from  photo- 
graphic plate  ;  76  mm.  (3  in.)  by  25  mm.  (i  in.)  is  the 
standard  size. 

Cover  glasses  must  be  bought.  They  should  be  15  to 
20  mm.  in  diameter  or  square.  No.  2  thickness  is  pref- 
erable. 

The  compound  microscope  should  be  of  good  work- 
manship, which  can  be  best  secured  by  buying  of  some 
reputable  maker.  A  small  low  stand  is  to  be  pre- 
ferred. It  should  have  a  good  fine  adjustment  and  be 
furnished  with  two  good  objectives,  viz.,  a  I  in.,  £  or  §, 
and  a  £,  \,  or  £,  and  two  eye-pieces,  viz.,  A  and  C,  or  if 
only  one,  a  B.  A  combination  of  either  eye-piece  with 
the  i  in.,  f,  or  §  is  in  this  manual  designated  as  a  "low 
power"  ;  similarly,  a  combination  with  the  j,  £,  or  -J- 
is  known  as  a  "  high  power."  There  should  also  be  a 
camera  lucida,  and  a  micrometer  ruled  in  fractions  of  a 
millimeter. 

Fine  forceps  should  be  of  steel,  have  very  slender 
bent  points,  and  come  together  accurately.  Those  used 
by  dentists  are  excellent. 

A  large  camels-hair  brush  \s  desirable  for  dusting  off 
lenses.  A  small  one  with  long  hairs,  which  tapers  to  a 
sharp  point  when  wet,  is  very  convenient  for  removing 
sections  from  the  razor.  It  should  be  mounted  on  the 
small  end  of  a  pen-holder,  in  the  large  end  of  which  is 
a  short  needle.  By  sticking  this  in  the  table  the  brush 
may  be  kept  out  of  the  dust  and  always  handy. 

Watch-glasses  should  have  a  flat  bottom  to  prevent 
tipping  too  easily.  Plain  individual  salt-cellars  answer 
the  purpose  admirably. 

A  dropping-tube  is  a  piece  of  small  glass  tubing  drawn 


4  INTRODVCTtOtf. 

to  a  point,  with  a  rubber  bulb  on  the  larger  end.  They 
may  be  purchased  in  drug  stores  under  the  name  of 
"  medicine  droppers." 

Fine  scissors  may  be  either  those  made  for  anatom- 
ical purposes  or  small  embroidery  scissors.  The 
latter  answer  most  purposes  well. 

A  metric  rule  is  highly  desirable.  The  student 
should  have  a  pocket  rule  and  should  early  familiarize 
himself  with  the  metric  system.  Metric  measures  of 
various  styles  and  prices  may  be  obtained  of  the  Amer- 
ican Metric  Bureau,  Boston,  Mass. 

The  drawing  materials  required  consist  of  slips  or  a 
blank  book8  of  unruled  paper,  hard  and  soft  pencils, 
pens  and  ink.  For  ink  drawings  the  paper  may  be 
either  sized  or  unsized,  rough  or  smooth,  so  long 
as  the  ink  does  not  spread,  but  for  pencil  drawings 
the  surface  must  be  minutely  roughened,  and  with- 
out sizing,  in  order  that  the  plumbago  may  adhere  well 
and  give  a  soft  effect.  A  quite  hard  pencil,  No.  5,  VH 
or  HHHH,  of  artists'  grades,  is  needed  for  tracing 
under  the  camera  lucida,  and  one  slightly  softer  than 
used  for  ordinary  writing,  No.  2,  SM,  or  B,  for  com- 
pleting drawings,  especially  those  in  gross  anatomy. 
Ordinary  steel  pens,  preferably  those  with  slender 
points,  and  common  black  ink  will  suffice,  but  finer 
work  may  be  done  with  lithographic  pens  and  India 
ink. 

II.  REAGENTS. 

The  following  reagents  are  necessary  for  the  study 
of  minute  anatomy  with  this  manual : 

2  If  a  book  is  used  it  must  be  so  bound  that  it  will  lie  flat  on  the  table 
when  open.  The  slips  are  usually  preferred. 


IXTRODUCTIOX.  $ 

Alcohol,  Magenta, 

Potassic  hydrate,  Glycerine, 

Iodine,  Sulphuric  acid, 

Chlor-iodide  of  zinc.  Potassic  chlorate  solution. 

The  alcohol  used  is  the  commercial  article,  95  per 
cent.  pure. 

The  potassic  hydrate  is  a  5  per  cent,  solution  of 
potassic  hydrate  in  distilled  water.  Sodic  hydrate  will 
answer  the  same  purpose.  The  "  liquor  potassae  "  of 
the  U.  S.  Dispensatory  is  of  this  strength  and  may  be 
purchased  of  any  druggist. 

The  iodine  is  prepared  as  follows :  Dissolve  3  gm.  of 
iodide  of  potassium  in  350  cc.  of  distilled  water  ;  add  I 
gm.  of  sublimed  iodine.  A  weaker  solution  will  be 
useful,  viz.,  potassic  iodide  3  gm.,  distilled  water  500 
cc.,  iodine  I  gm.  The  tincture  of  iodine  diluted  till  it 
is  a  sherry  brown  color  will  answer  in  some  cases,  but 
is  not  so  generally  useful  as  the  solution  recom- 
mended. 

Chlor-iodide  of zinc  may  be  prepared  as  follows:  Dis- 
solve metallic  zinc  in  concentrated  hydrochloric  acid 
until  the  action  ceases ;  evaporate  to  the  consist- 
ency of  syrup  in  contact  with  metallic  zinc  ;  saturate 
this  with  potassic  iodide  ;  add  as  much  iodine  as  it  will 
take  up,  with  some  excess.3  It  is  better  to  keep  the 
solution  in  a  dark  place,  although  in  the  majority  of 
instances  the  proper  reaction  will  be  secured  without 
this  precaution. 

Magenta  is  a  solution  of  the  aniline  color   of  that 
name.     It  may  be  purchased  of  dealers  in  microscopi- 
cal supplies  or  made  as  follows :  Powder  I  gm.  crystal- 
3  Poulsen  and  Trelease,  Bot.  Micro-Chemistry,  p.  8. 


6  IN  TROD  UC  TION. 

lized  magenta.  Dissolve  in  160  cc.  distilled  water,  to 
which  I  cc.  of  alcohol  has  been  added.4 

The  best  commercial  glycerine  should  be  used.  See 
that  it  is  colorless  and  free  from  sediment. 

A  75  per  cent,  solution  of  sulphuric  acid  should  be 
prepared  by  mixing  three  volumes  of  c.  p.  sulphuric 
acid  with  one  volume  of  distilled  water,  being  very 
careful  to  pour  the  acid  slowly  into  the  water  while 
stirring  it. 

The  potassic  chlorate  solution  may  be  prepared  as  fol- 
lows :  Dissolve  2  gm.  potassic  chlorate  in  5  cc.  nitric 
acid. 

III.  USE  OF  THE  MICROSCOPE  AND  LENS. 

The  prime  requisite  in  the  use  of  any  optical  instru- 
ment is  cleanliness:  dirty  lenses  frequently  defeat  the 
very  object  of  their  use,  namely,  clearer  vision.  Before 
beginning  to  work  with  either  the  simple  or  compound 
microscope,  see  that  the  lenses  are  perfectly  clean. 
When  a  lens  needs  cleaning,  take  a  camel's-hair  brush 
and  brush  away  all  particles  of  dust.  Then  wipe  gently 
with  a  piece  of  soft  unstarched  linen  or  cotton — an  old 
handkerchief  is  the  best— breathing  upon  the  surface 
slightly  if  necessary  to  remove  the  dirt.  Too  great  care 
can  not  be  taken  to  avoid  scratching  the  polished  surface 
of  the  lens  ;  hence  the  least  possible  effective  pressure 
should  be  used  when  wiping  it.  If  properly  handled 
after  they  have  once  been  cleaned,  lenses  will  seldom 
need  any  thing  but  brushing.  One  should  avoid  with 
the  greatest  care  touching  the  surface  of  a  lens  with 

4  Huxley  and  Martin,  Biology,  p.  269. 


INTRODUCTION.  7 

the  fingers,  as  finger  marks  are  difficult  to  remove  :  no 
matter  how  clean  the  skin,  the  oil  from  it  will  adhere  to 
the  glass  and  can  only  be  perfectly  removed  by  wiping 
with  linen  moistened  with  alcohol. 

When  the  lens  is  held  in  the  hand  to  examine  ob- 
jects, rest  the  hand  holding  the  lens  on  the  hand  hold- 
ing the  object.  They  will  then  tremble  together.  The 
eye  should  be  as  close  to  the  lens  as  possible  in  order 
to  obtain  a  wider  field  of  view. 

In  using  the  compound  microscope  the  front  only  of 
the  objective  and  both  surfaces  of  both  lenses  of  the 
eye-piece  need  cleaning.  If  the  eye-piece  be  dirty  there 
will  be  specks  in  the  field  of  view  when  there  is  no  ob- 
ject on  the  stage.  These  can  be  made  more  apparent 
by  turning  the  eye-piece  in  the  tube  while  looking 
through  it.  In  like  manner  by  partly  unscrewing  the 
eye  lens  and  turning  it,  it  may  be  discovered  whether 
the  eye  lens  or  field  lens  is  dirty.  If  the  front  of  the 
objective  be  dirty  it  will  be  manifested  by  a  dimness 
and  want  of  definition  of  the  outlines  of  objects,  affect- 
ing the  whole  field  of  view. 

In  focusing  with  the  high  power  of  the  compound 
microscope,  first  rack  the  objective  down  as  close  to  the 
cover-glass  as  possible  while  watching  it  from  one  side. 
Then  look  through  the  tube,  rack  slowly  back  and 
watch  for  the  coming  of  the  object  into  view. 

Never  rack  downwards  while  looking  through  the 
tube  unless  the  object  be  in  view. 

Do  not  use  the  fine  adjustment  until  the  object  is 
nearly  in  focus  with  the  coarse. 

Raise  the  objective  slightly  before  placing  or  remov- 
ing a  slide. 


8  INTRODUCTION. 

An  object  is  examined  by  "  direct "  light  when  it  is 
examined  by  the  light  which  falls  upon  its  surface  with- 
out passing  through  it.  This  is  the  common  method 
with  the  hand  lens. 

An  object  is  examined  by  "  transmitted  "  light  when 
the  light  passes  through  it  before  entering  the  eye. 
This  is  the  common  method  with  the  compound  mi- 
croscope. Ordinarily,  when  transmitted  light  is  used, 
direct  light  should  be  cut  off  as  far  as  possible. 

An  object  is  examined  by  "  oblique  "  light  when  the 
light  passes  through  it  so  obliquely  that  only  that  re- 
fracted by  the  object  enters  the  eye.  It  therefore  ap- 
pears light  against  a  dark  ground. 

IV.  SECTION  CUTTING. 

Sections. — A  section  is  a  very  thin  slice  taken  from  the 
interior  of  any  organ.  It  should  be  of  as  nearly  equal 
thickness  in  all  parts  as  possible.  The  term  "  slice  "  is 
used  to  designate  a  thin  piece  cut  from  the  surface  of 
any  organ. 

By  a  transverse  section  is  meant  one  at  right  angles 
to  the  long  axis  of  the  object.  Unless  care  is  exercised 
the  surface  from  which  the  sections  are  being  cut  will 
become  inclined.  Especially  is  this  likely  when  the 
object  is  large  or  is  supported  in  pith.  The  pith  stick 
should  be  trimmed  down  at  the  end  so  as  to  leave  only 
enough  to  support  the  object.  The  chief  cause  of  the 
tendency  to  become  inclined  is  that  the  under  side  of 
the  razor  is  not  flat ;  hence  the  larger  the  object,  the 
more  likely  the  transverse  sections  are  not  to  be  truly 
transverse. 

By  a    longitudinal  section   is   meant   one  which  is 


INTRODUCTION.  9 

parallel  to  or  includes  the  long  axis  of  the  object.  It  is 
evident  that  longitudinal  sections  of  all  cylindrical  ob- 
jects may  be  either  radial  or  tangential.  A  radial 
section  is  one  lying  in  the  plane  of  a  radius.  A  tangen- 
tial section  is  one  parallel  to  a  plane  tangent  to  the 
cylinder. 

Longitudinal  sections  are  much  more  difficult  to 
make  than  transverse  and  they  are  nearly  or  quite  use- 
less unless  truly  longitudinal. 

The  razor. — The  secret  of  making  good  sections 
lies  in  having  and  keeping  a  sharp  razor.  No 
amount  of  skill  can  make  a  dull  razor  cut  a  thin 
section. 

The  edge  of  the  razor  must  be  free  from  nicks.  This 
can  be  determined  by  looking  at  the  profile  of  the  edge 
against  a  bright  light  with  a  lens.  Nicks,  if  small,  can 
easily  be  taken  out  on  a  hone. 

The  razor  should  be  stropped  often.  It  is  easier  to 
keep  it  from  getting  dull  than  to  sharpen  it  after  it  has 
become  so.  If  its  edge  is  free  from  nicks  and  it  will  cut 
a  hair  of  the  head  2  cm.  from  where  it  is  grasped  by  the 
fingers,  it  is  in  good  condition. 

After  using  the  razor  be  careful  to  see  that  no  mois- 
ture or  plant  juices  are  left  on  the  blade;  they  will 
surely  rust  it  if  allowed  to  remain. 

Holding  specimens. — Large  specimens  of  which 
sections  are  to  be  cut  may  easily  be  held  in  the 
fingers.  They  should  be  held  vertical,  grasped 
by  the  fore-finger  and  thumb  of  the  left  hand 
so  that  the  razor  blade  may  rest  on  the  cor- 
ner of  the  fore-finger,  and  the  remainder  of  the  hand 
be  out  of  the  way  below. 


10  INTRODUCTION. 

Small  objects  should  be  placed  in  a  piece  of  elder  or 
sunflower  pith  in  which  a  median  longitudinal  slit  has 
been  made,  deep  enough  to  allow  the  ends  to  spring  as 
far  apart  as  necessary  to  receive  the  specimen,  between 
which  it  is  to  be  firmly  held.  The  pith  is  then  to 
be  grasped  as  a  large  specimen  for  cutting.  If  alcoholic 
specimens  are  being  used  the  pith  should  be  pre- 
viously soaked  in  alcohol,  and  if  fresh  material,  in 
water. 

Cutting. — Grasp  the  razor  firmly  with  the  right  hand 
where  the  blade  joins  the  handle,  bracing  the  blade  by 
resting  the  thumb  against  the  tang.  Hold  the  razor  hor- 
izontal, rest  the  under  side  of  the  blade  against  the  corner 
of  the  fore-finger  and  cut  toward  you,  pushing  the  razor 
from  point  to  tang  or  drawing  it  in  the  opposite 
direction,  using  as  much  of  the  blade  in  cutting  as 
possible. 

If  the  object  be  flat  and  thin,  as  a  leaf,  let  the  razor 
edge  pass  through  it  at  an  angle  of  20°  to  30°  to  its 
length. 

If  alcoholic  specimens  are  being  cut,  the  razor  blade 
should  be  flowing  with  alcohol.  The  oil  usually  on  the 
blade  from  stropping  will  prevent  the  alcohol  from  run- 
ning off,  unless  the  blade  be  considerably  inclined.  If 
fresh  material  is  used  the  razor  should  be  dipped  in 
water.  The  object  of  the  operation  in  both  cases  is  to 
prevent  the  section  from  becoming  dry.  Should  it  do 
so,  it  will  inevitably  contain  air  bubbles  when  mounted, 
which  will  unfit  it  for  examination. 

Removing  the  sections. — The  most  convenient  thing 
for  removing  sections  from  the  razor  is  a  small  camel's- 
hair  brush,  which,  when  wet,  tapers  to  a  sharp  point. 


INTRODUCTION.  li 

With  such  a  brush  a  section  may  easily  be  picked  up 
from  the  water  or  alcohol,  in  which  it  ought  to  be 
floating  on  the  razor,  and  transferred  either  to  the  slide 
or  to  a  watch  glass.  An  easier  way  of  removing  sec- 
tions which  are  to  be  transferred  to  a  watch  glass,  is 
to  wash  them  down  to  the  point  of  the  razor,  and  then 
dip  the  point  of  the  blade  in  the  liquid  in  the  watch 
glass. 

Always  cut  a  number  of  sections — half  a  dozen  or 
more — at  once.  One  or  more  may  prove  good. 

V.  MOUNTING. 

Previous  to  mounting  any  specimens,  it  must  be  seen 
that  the  slide  and  cover  glass  are  perfectly  clean. 
Nothing  is  better  for  cleaning  slides  and  covers  than  a 
clean  linen  handkerchief,  which  should  be  used  for  this 
purpose  alone.  The  cleaning  of  the  slide  is  a  simple 
operation  ;  the  cleaning  of  the  cover  requires  more  care, 
to  prevent  breaking.  Having  dipped  the  cover  in  clean 
water,  take  it  between  the  thumb  and  fore-finger,  over 
which  a  single  thickness  of  the  handkerchief  has  been 
thrown.  Wipe  gently,  using  the  fingers  of  the  other 
hand  to  keep  it  in  place.  The  surfaces  of  the  cover 
should  be  perfectly  cleaned,  so  that  when  light  is 
reflected  from  them,  no  oiliness  or  dust  is  visible. 
Having  cleaned  the  cover,  lay  it  down  in  some  clean 
place,  with  one  edge  projecting  slightly,  so  that  it  can 
be  readily  picked  up,  or  stand  it  on  edge  against  some 
support.5  Having  placed  the  desired  specimen 

5  A  very  convenient  receptacle  for  covers,  whether  clean  or  dirty,  is 
made  by  sawing  several  grooves  in  a  block  of  wood,  and  nailing  across 
the  ends  of  the  grooves  a  thin  strip.  In  these  grooves  the  covers  rest  on 
edge.  A  similar  arrangement  is  useful  for  slides. 


1 2  IN  TROD  UCTIOtf. 

in  the  center  of  the  slide  in  a  drop  of  water, 
grasp  the  edge  of  the  cover  firmly  with  the  fine 
forceps,  breathe  on  the  under  side,  hold  it  in  a  slanting 
position  over  the  drop  of  water,  place  the  lower  edge 
in  the  edge  of  the  drop,  and  lower  it  gradually  on  the 
water.  The  condensed  moisture  of  the  breath  insures 
more  ready  contact  of  the  water  with  the  cover,  and 
lowering  the  cover  slantwise  gives  opportunity  for  the 
escape  of  air  from  under  it. 

If  air  bubbles  appear  in  the  mounting,  they  are  due 
to  one  of  two  reasons  :  either  (i)  the  cover  glass  was 
not  clean,  or  (2)  it  was  dropped  instead  of  being  low- 
ered to  the  slide.  Of  these  the  first  is  the  more  com- 
mon cause  of  air  bubbles.  They  may  sometimes  be 
removed  by  lifting  one  edge  of  the  cover  with  a  needle, 
while  the  other  is  prevented  from  slipping,  and  then 
lowering  again.  Sometimes  it  will  be  necessary  to 
remove  the  cover,  clean  and  replace  it. 

If  the  bubbles  appear  in  the  specimen  itself,  they  are 
probably  caused  by  allowing  the  section  to  dry  partly 
before  mounting.  They  may  usually  be  removed  by 
taking  off  the  cover  and  treating  the  specimen  with 
alcohol. 

The  worker  should  not  be  content  to  let  bubbles 
remain. 

Another  difficulty  is  sometimes  encountered,  when 
it  is  attempted  to  mount  several  sections  under  the 
same  cover,  in  the  floating  out  of  one  or  more.  This 
is  usually  due  to  an  excess  of  water.  The  remedy  is  to 
take  up  the  cover,  absorb  some  of  the  water  with  filter 
paper,  and  re-cover. 

After  covering  specimens,  soak  up  the  superfluous 


INTRODUCTION.  13 

liquid  sufficiently  to  prevent  the  cover  floating  when 
the  slide  is  inclined. 

VI.  APPLYING  REAGENTS. 

Stains  are  most  conveniently  applied  by  placing  a 
drop  of  the  liquid  at  the  edge  of  the  cover,  and  allow- 
ing it  to  run  under,  hastening  the  process  when  desired 
by  placing  a  strip  of  filter  paper  at  the  opposite  edge. 
If  the  stain  does  not  reach  all  parts  of  the  specimen, 
the  cover  glass  may  be  slightly  raised.  It  is  quite 
important  in  many  cases  to  watch  the  action  of  reagents. 
In  such  a  case  they  should  be  applied  with  the  stage  of 
the  microscope  horizontal.  Time  may  be  saved  when 
it  is  necessary  to  examine  specimens  in  potash,  by 
placing  a  drop  of  potash  on  the  slide,  and  mounting 
directly  in  that  medium.  In  all  cases,  as  soon  as  the 
specimens  have  become  clear,  the  potash  should  be 
washed  out  with  water:  otherwise  the  cell  walls  swell 
excessively,  and  many  points  become  indistinguishable. 
It  should  be  remembered  in  examining  specimens 
treated  with  potash  that  many  cell  walls  are  somewhat 
swollen,  and  that  the  longer  they  remain  the  greater 
the  swelling  becomes. 

Glycerine  is  one  of  the  most  useful  media  for  clear- 
ing, and  at  the  same  time  preserving  specimens  for 
prolonged  examination.  Whenever  it  becomes  desir- 
able to  preserve  specimens  from  one  day  to  another,  a 
drop  of  glycerine  should  be  applied  to  the  slide,  so 
that  it  just  touches  the  edge  of  the  cover,  and  the  slide 
laid  away  in  a  horizontal  position.  As  the  water  or 
alcohol  evaporates,  the  glycerine  will  run  under  the 
cover.  The  excess  may  be  wiped  off  with  a  damp  rag 


1 4  IN  TROD  UCTION. 

after  a  few  hours.  Specimens  may  be  mounted  directly 
from  alcohol  or  water  in  glycerine,  but  the  saving  in 
time  will  not  be  material,  unless  it  is  known  that  the 
specimens  are  good,  before  mounting.  Care  must  be 
taken  that  the  glycerine  does  not  overspread  the  cover, 
which,  under  such  condition,  must  be  taken  off  and 
cleaned.  Most  specimens  may  remain  in  glycerine  any 
length  of  time  without  deterioration,  and  will  become 
clearer  and  clearer  all  the  time.  Care  must  be  taken  to 
keep  the  specimens  thus  preserved  free  from  dust. 
They  must  be  handled  cautiously,  lest  the  cover  be 
shoved  off.  If  desired,  specimens  which  have  been 
preserved  in  glycerine,  may  be  permanently  mounted, 
by  simply  running  a  ring  of  shellac  cement  around  the 
cover.6 

The  greatest  care  must  always  be  exercised  to  pre- 
vent reagents  from  coming  in  contact  with  the  stand 
of  the  microscope  or  the  lenses,  as  most  of  them  attack 
the  lacquer  of  the  brass  work,  and  some  the  brass. 
The  chief  danger  arises  from  a  failure  to  remove  the 
excess  of  the  reagent,  which  then  collects  at  the  lower 
edge  of  the  slide  when  the  microscope  is  used  in  an 
inclined  position,  and  runs  off  on  the  stage.  Sulphuric 
acid  behaves  in  the  same  way  even  when  the  excess 
is  once  removed,  if  it  is  allowed  to  remain  any  length 
of  time,  because  it  absorbs  moisture  from  the  air. 

Boiling  specimens  in  the  potassic  chlorate  solution 
should  not  be  done  in  the  same  room  with  the  micros- 
cope as  the  liquid  and  its  fumes  are  intensely  corro- 
sive. 

6  For  directions  for  making  this  cement,  see  Am.  Mo.  Mic.  Jour.,  vt 
(1884),  p.  131.  Similar  cements  may  be  bought. 


IN  TR  OD  UC  TION.  1 5 

VII.  CARE  AND  USE  OF  MATERIAL. 

Throughout  the  directions  for  laboratory  work  it  is 
understood  that  material  preserved  in  alcohol  will 
answer  unless  otherwise  stated.  In  many  cases  only 
alcoholic  specimens  are  usable  and  in  other  cases  only 
fresh  specimens. 

Do  not  tear  up  specimens  needlessly. 

Examine  a  specimen  thoroughly  and  see  as  much  as 
possible  before  dissecting. 

Do  not  begin  dissecting  a  part  until  it  is  decided 
what  to  look  for  and  where  to  look  for  it. 

Be  economical  ;  chiefly  because  it  is  a  good  habit, 
secondarily  because  material  costs  time,  or  money,  or 
both. 

Save  the  pieces  ;  they  may  be  useful  in  future  work  : 
it  is  easy  to  throw  away  ;  it  is  more  difficult  to  gather. 

Preserve  all  sections  and  other  preparations  until  the 
study  of  the  plant  is  completed. 

When  the  specimens  are  mounted  in  water  be  care- 
ful lest  they  become  dry  by  the  evaporation  of  the 
water.  It  can  be  most  conveniently  replaced  by  plac- 
ing a  brush  charged  with  water  at  the  edge  of  the 
cover  opposite  the  area  of  air.  As  soon  as  the  air  is 
displaced  the  brush  should  be  removed. 

When  studying  particular  tissues  in  a  section  the 
thinnest  parts  of  each  tissue  should  be  selected.  It  is 
rare  that  a  section  is  so  uniform  that  the  tissues  are 
equally  well  shown  in  all  parts  of  it,  and  different  tissues 
must  not  infrequently  be  looked  for  in  different  sec- 
tions. It  is  best  therefore  to  look  well  over  the  speci- 
mens before  settling  to  the  study  of  any  tissue. 

In  order  to  obtain  a  clear  conception  of  the  shapes 


1 6  INTRODUCTION. 

of  the  cells  of  a  particular  tissue,  it  is  indispensable  that 
the  student  carefully  compare  the  transverse  and  longi- 
tudinal sections  of  the  cells.  Moreover  the  longitudi- 
nal sections  must  be  compared  with  the  transverse  to 
determine  their  position. 

It  frequently  becomes  necessary  to  examine  a  toler- 
ably thick  object.  In  such  a  case,  very  different  views 
of  the  object  will  be  obtained  as  the  focusing  screw  of 
the  fine  adjustment  is  moved.  It  must  be  remembered 
that  a  good  objective  gives  a  clear  image  of  only  a 
single  plane  at  one  time,  though  adjacent  images 
modify  this  somewhat.  Hence  it  is  easy  to  determine, 
knowing  in  which  direction  the  objective  is  moved  by 
the  focusing  screw,  whether  one  object  is  above  or 
below  another. 

The  use  of  the  fine  adjustment  must  be  learned  as 
soon  as  possible  and  must  be  assiduously  practiced. 
The  finger  should  be  kept  on  the  fine  adjustment  most 
of  the  time  when  using  high  powers,  and  nothing 
allowed  to  escape  the  vision  which  the  fraction  of  a 
turn  would  reveal. 

VIII.  DRAWING. 

In  the  systematic  examination  of  an  object  two  kinds 
of  memoranda  should  be  made,  descriptions  and 
drawings.  The  value  of  the  former  is  usually  conceded, 
but  that  of  the  latter  is  often  deemed  too  slight  to  re- 
pay the  trouble.  The  importance  of  drawing  can  not, 
however,  be  too  strenuously  urged,  and  the  difficulty 
and  tediousness  of  execution,  which  will  largely  dis- 
appear with  practice,  should  never  be  offered  as  an 
excuse  for  its  neglect. 


INTRODUCTION.  l^ 

Drawing  may  represent  the  object  with  various 
degrees  of  fidelity.  At  one  extreme  is  the  diagram 
(see  fig.  i),  which  only  aims  to  give  the  relative  posi- 
tions or  sizes  of  the  several  parts,  or  some  other  feat- 
ure. At  the  other  extreme  the  drawing  is  as  close  a 
counterpart  of  the  object  seen  as  the  person  who  draws 
it  is  capable  of  producing  (see  fig.  3).  Whether  a  par- 
ticular object  shall  be  drawn  in  one  way  or  the  other, 
or  in  some  intermediate  way,  must  be  determined 
by  the  nature  of  the  object  and  the  end  to  be  attained 
by  the  study. 

The  usual  tendency  is  to  make  drawings  too  small ; 
they  should  be  large  enough  to  show  all  parts  dis- 
tinctly without  close  scrutiny. 

Drawings  may  usually  be  satisfactorily  made  in  out- 
line, or  with  very  little  shading,  as  in  fig.  4  or  6.  They 
are  most  easily  drawn  with  a  soft  pencil  on  heavy, 
unsized  and  slightly  calendered  paper,  producing  the 
effect  in  fig.  3  or  10,  but  are  not  permanent ;  rubbing 
readily  defaces  them,  unless  treated  to  a  fine  spray  of 
colorless  shellac  dissolved  in  alcohol,  which  may  be 
applied  with  an  atomizer,  such  as  is  used  for  perfumery. 
Ink  drawings  are  to  be  preferred  fortheirdurability  and 
distinctness.  When  ink  is  used,  the  main  features  of  the 
drawing  should  first  be  lightly  sketched  with  a  hard 
pencil,  and  the  pencil  marks  erased  after  the  ink  is  dry. 

Drawings  in  gross  anatomy  should  be  the  exact  size 
of  the  object,  or  some  multiple  of  it.  Record  the 
amount  of  linear  enlargement  by  a  number  placed 
at  one  side  of  the  drawing  with  an  oblique  cross 
prefixed. 

In    the    directions    for    laboratory  work    in    gross 


1 8  INTRODUCTION". 

anatomy  the  number  of  drawings  has  been  mostly  left 
to  the  discretion  of  the  student. 

In  minute  anatomy  the  points  at  which  drawings 
may  most  profitably  be  made  are  carefully  noted.  In 
many  instances,  however,  it  is  so  difficult  to  secure  a 
wholly  satisfactory  section  to  show  certain  structures, 
that  they  should  be  drawn  whenever  found  in  good 
condition,  without  regard  to  the  directions. 

Drawings  in  minute  anatomy  may  be  either  free- 
hand or  with  camera  lucida.  In  free-hand  drawing  the 
student  is  especially  cautioned  against  making  them 
too  small,  which  is  a  very  common  fault.  In  the  out- 
lines for  work  it  is  expected  that  accurate  drawings  be 
made  unless  a  diagram  or  diagrammatic  drawing  is 
called  for.  A  diagram  (fig.  11)  shows  only  a  single 
special  feature,  or  at  most  two  or  three,  while  a  dia- 
grammatic drawing  (fig.  8  or  10)  shows  all  the  chief 
features,  but  does  not  take  note  of  smaller  matters, 
such  (e.  g.)  as  distinguish  the  several  cells  of  the  same 
tissue.  When  an  accurate  drawing  is  to  be  made,  each 
individual  cell  should  be  drawn  as  carefully  as  if  it 
were  the  whole  object.  When  an  accurate  drawing 
includes  considerable  tissue,  time  may  be  saved  by 
indicating  the  boundaries  between  the  tissues  by  dot- 
ted outlines,  and  only  cells  enough  filled  in  to  show 
the  character  of  the  tissues. 

In  order  to  draw  to  scale  with  the  microscope  it  is 
necessary  to  use  a  camera  lucida.  The  magnification 
is  thus  determined  :  place  a  micrometer  on  the  stage 
of  the  instrument  in  the  same  position  as  an  object, 
adjust  the  instrument  as  for  drawing,  and  laying  a 
common  rule  on  the  drawing  paper  read  off  the  dis- 


IN  TROD  UCTION.  1 9 

tance  that  the  image  of  one  division  of  the  stage 
micrometer  covers  on  the  rule.  If,  for  instance,  a  tenth 
of  a  millimeter  of  the  stage  micrometer  covers  five 
centimeters  (five  hundred  tenths  of  a  millimeter),  any 
drawing  under  the  same  adjustment  will  be  magnified 
five  hundred  times.  -Always  mark  the  number  of 
times  magnified  at  the  side  of  the  drawing  as  in  gross 
anatomy,  thus,  x  500. 

The  distance  from  the  drawing-paper  to  the  reflecting 
surface  of  the  camera  lucida  should  be  about  the  same 
as  from  the  latter  to  the  outer  lens  of  the  object  glass, 
in  order  that  the  drawing  may  properly  represent  the 
magnifying  power  of  the  instrument.  Ten  inches  has 
been  adopted  as  the  standard  length  of  tube. 

Trace  the  image  first  with  a  hard  pencil,  and  then 
go  over  it  with  ink  before  the  object  is  removed  from 
the  instrument  in  order  to  correct  any  errors  made  by 
the  pencil. 

It  is  not  an  easy  matter  to  draw  accurately  with  the 
camera  lucida,  owing  to  the  difficulty  in  seeing  both 
the  image  and  the  pencil  point  distinctly  at  the  same 
time.  Much  depends  on  the  relative  amount  of  light 
received  by  the  eye  from  the  instrument  and  from  the 
drawing-paper.  If  the  pencil  point  does  not  show 
clearly,  there  should  be  more  light  on  the  paper,  and 
if  the  image  is  not  clear,  more  on  the  object. 

Invariably  accompany  each  drawing  with  a  full  expla- 
nation. 

IX.  BOOKS  OF  REFERENCE. 

It  should  be  the  aim  of  the  student  to  find  out  all 
that  he  can  about  the  plant  in  hand  with  as  little  assist- 


20  INTRODUCTION. 

ance  as  possible  or  without  any.  This  requires  patient 
and  thorough  work.  When  done,  however,  and  draw- 
ings and  notes  have  been  fully  recorded,  it  will  be 
advantageous  to  compare  the  work  with  the  published 
observations  of  others,  and  if  any  points  have  been 
overlooked  or  misunderstood,  to  go  over  the  ground 
again. 

The  following  general  treatises  will  be  found  suita- 
ble for  preliminary  consultation,  and  when  possible 
should  be  constantly  at  hand  on  the  laboratory  shelves  : 
Gray's  Structural  Botany,  Goodale's  Physiological 
Botany,  Bessey's  Botany  for  High  Schools  and  Col- 
leges, Sachs'  Text  Book,  2nd  Eng.  edition,  Prantl  and 
Vines'  Text  Book  of  Botany,  DeBary's  Comparative 
Anatomy  of  Phanerogams  and  Ferns,  Strasburger's 
Das  botanische  Practicum,  Poulsen  and  Trelease's 
Botanical  Micro-Chemistry. 

If  the  student  becomes  interested  in  any  particular 
direction,  the  references  given  in  the  annotations, 
together  with  those  to  be  found  in  such  of  the  works 
just  named  as  may  be  at  hand,  will  usually  give  him  a 
fair  start  in  tracing  the  literature  of  the  subject,  and 
becoming  acquainted  with  what  has  already  been  ascer- 
tained in  regard  to  it.  This  will  indicate  wherein 
present  information  is  defective,  and  enable  him  to 
direct  his  labors  toward  a  profitable  increase  of  the 
total  sum  of  knowledge. 

The  references  have  been  preferably  to  works  most 
likely  to  be  at  the  student's  command,  whenever  these 
have  contained  a  sufficiently  full  treatment,  this  doubt- 
less tending  more  to  accomplish  the  desired  object 
of  interesting  the  student  and  leading  him  on  to 


INTRODUCTION.  21 

independent  work,  than  references  in  all  cases  to  the 
original  sources  of  information.  Less  accessible  works 
have  often  been  cited  to  introduce  the  student  at 
once  to  the  most  complete  treatment  of  the  subject. 
A  few  citations  are  for  the  sake  of  authority. 

Many  of  the  memoirs  and  articles  cited  in  apparently 
inaccessible  foreign  journals  and  proceedings  of  socie- 
ties may,  however,  be  bought  separately  of  foreign 
dealers  (R.  Friedlander  &  Sohn,  Berlin  N.  W.,  Ger- 
many, and  many  others).  A  very  moderate  outlay 
will  thus  enable  one  to  consult  numerous  valuable 
writings. 

No  apology  need  be  offered  for  referring  in  an 
elementary  work  to  writings  in  foreign  languages,  for 
unless  the  student  carries  his  researches  outside  this 
manual  he  will  have  no  occasion  to  use  them,  and  if 
he  does  do  so  he  can  not  go  far  without  being  obliged 
to  use  them.  It  is  not  often  possible  in  fact  to  treat  a 
subject  exhaustively  in  the  departments  of  botany 
covered  by  this  handbook  without  a  knowledge  of 
German  and  French  writings  at  least. 

But  if  the  references  given  among  the  annotations 
are  never  used,  they  will  still  serve  a  good  purpose  in 
impressing  upon  the  learner  that  he  is  only  upon  the 
threshold  of  the  study,  and  that  the  facts  which  he 
seems  to  be  gathering  so  thoroughly  are  in  most  cases 
to  be  found  more  fully  and  accurately  set  forth  in  the 
great  storehouse  of  learning  beyond. 


GREEN    SLIME. 

Protococcus  viridis  Ag. 


PRELIMINARY. 

THE  plant  selected  to  illustrate  the  simplest  phase'of 
vegetable  life  is  found  in  all  parts  of  the  United 
States,  and  even  throughout  the  world.  It  grows 
upon  the  surface  of  various  objects,  being  often  so 
abundant  as  to  give  them  a  conspicuous  green  color, 
especially  upon  the  north  side  of  old  fences,  barns, 
and  the  trunks  of  trees,  becoming  more  noticeable 
after  a  few  days  of  damp  weather.  There  are  several 
other  closely  related  species  that  may  be  used,  in 
fact  almost  any  unicellular  green  plant  will  answer, 
but  this  is  the  one  most  likely  to  be  gathered.  Some 
kinds  of  unicellular  plants,  like  Gl&ocapsa,  have  a 
sheath  or  envelope  outside  the  cell  proper,  not  found 
in  Protococcus,  a  fact  to  be  borne  in  mind  by  the 
student  if  such  plants  are  used.  Pieces  of  bark  or 
wood  bearing  the  alga  may  be  kept  dry  for  use,  and 
will  give  a  fresh  appearance  when  moistened  with 
water,  and  even  retain  vitality  for  a  year  or  two. 

It  is  quite  likely  that  the  plants  known  under  the 
name  of  Protococcus  are  but  early  forms  of  some  more 
complex  algae1,  but,  however  this  may  be,  they  serve 

1  Bessey,  Botany,  p.  219 ;  Wood,  Fresh-Water  Algae  of  North 
America,  p.  10 ;  Sachs,  Text-Book  of  Botany,  2nd  Eng.  ed.,  p.  248  ; 
Cienkowski,  Bot.  Zeit.  1876,  p.  17. 


PROTOCOCCUS  VIRIDIS.  23 

quite  as  well  as  any  to  illustrate  the  simplest  kind  of 
plant  life. 

To  complete  the  following  study  it  will  be  necessary 
to  have  pieces  of  wood  bearing  the  Protococcus ;  iodine  ; 
chlor-iodide  of  zinc  ;  and  alcohol. 

LABORATORY  WORK. 

GROSS  ANATOMY. 

Taking  either  a  fresh  or  dried  specimen,  notice 

1.  The  color. 

2.  The  evenness  with  which   the   plant   overspreads   the 
supporting  surface. 

Using  a  lens,  notice 

3.  The   pulverulent  appearance,  as  if    dusted  or  sanded 
upon  the  surface. 

4.  The   appreciable    thickness    reached   in   some   spots, 
causing  it  to  separate  in  scales  in  the  dried  specimen. 

Mount,  and  observe 

5.  The  dust-like  particles'1  into  which  it  separates. 

6.  The  varying  size  of  the  particles. 

Place  a  piece  of  bark  with  the  Protococcus  in  a  small 
quantity  of  alcohol,  after  an  hour  or  more  notice 

7.  The  color  imparted   to   the  alcohol  by  the    coloring 
matter  of  the  plant,  the  chlorophyll.3 

MINUTE  ANATOMY. 

Under  high  power,  notice 

8  Care  must  be  taken  not  to  confound  them  with  air  bubbles,  which 
are  often  numerous  when  a  dried  specimen  is  used. 

8  Some  less  common  forms  of  unicellular  algae  are  red  or  purple  from 
additional  coloring  matter. 


24  GREEN'  SLIME. 

1.  The   individual  cells;    either  single  or  associated   in 
families. 

2.  The  size  of  the  cells  ;  some  small,  some  several  times 
larger. 

3.  The  shape ;  when  free  and  when  in  families. 

4.  The  cell  contents ;  more  or  less  granular,  and  always 
green  from  the  presence  of  chlorophyll. 

5.  The     colorless      cell- wall     surrounding     each     cell. 
Press  upon  the  cover-glass  with  a  back  and  forth  move- 
ment, and  the  walls  to  many  of  the  cells  and  cell-families 
will    be    ruptured   and  their   contents   ejected,  when  the 
wall  can  be  easily  studied. 

Stain  with  iodine  and  notice 

6.  The  brownish-yellow  color  given  the  contents  of  the 
cell,  showing  the  presence  of  protoplasm. 

Stain   a   freshly   mounted    specimen   with    dilute   chlor- 
iodide  of  zinc,  and  after  an  hour  or  two4  notice 

7.  The  two  to  several  closely  packed  bodies  of  definite 
outline,   usually  overlapping,   forming  the  green  part 
of  the  cell,  the  chlorophyll  bodies,  best  seen  in  the 
largest,  single,  round  cells.5 

8.  The  small  round  body  nearly  in  the  center  of  the  cell, 
or  in  recently  divided  cells  near  the  partition  wall,  the 
nucleus.6 

9.  Occasionally  a  clear  space  between  the    chlorophyll 
bodies  and  the  cell  wall,  occupied  by  \hzprotoplasm. 

10.    Draw   a   few    cells   showing    chlorophyll  bodies   and 
nuclei. 

4  If  the  cells  are  properly  stained  they  will  usually  remain  green,  but  of  a 
brighter  and  more  bluish  hue. 

5  There  is  danger  of  mistaking  delicate  partition  walls  of  young  cells, 
which  the  reagent  has  thickened  and  made  visible,  for  the  boundaries  of 
the  chlorophyll  bodies. 

6  Under  higher  power  yet  a  central  dot  to  the  nucleus,  the  nucleolus, 
may  be  detected. 


PROTOCOCCUS  VIRIDIS.  25 

11.  The    cell  multiplication:    examine  various    specimens 
and  trace  the  successive  stages  in  the  division  of  a 
single  cell  to  form  a  cell  family. 

12.  Illustrate  the  cell  multiplication  by  drawings. 

ANNOTATIONS. 

Protococcus  is  a  unicellular  plant,  for  each  cell 
performs  individually  the  various  functions  pertaining 
to  plant  life  ;  and  this  is  true  whether  the  cells  remain 
single  or  become  associated  into  small  families. 

The  cell  is  the  unit  from  which  all  plants,  however 
complex,  are  built  up. 

The  most  essential  part  of  the  cell  is  the  protoplasm, 
a  colorless  semi-fluid  substance,  which  in  this  instance 
is  masked  by  the  green  chlorophyll.  It  is  the  only 
really  living,  active  agent  in  this,  as  well  as  in  all  other 
plants.  Its  presence  here  is  made  manifest  by  the 
characteristic  yellowish-brown  color  given  by  iodine. 

The  nucleus  (see  fig.  9  n)  is  a  special  form  of  the  pro- 
toplasm to  be  seen  in  most  plant-cells.  As  its  division 
usually  precedes  that  of  the  cell,  it  has  generally  been 
regarded  as  in  some  way  necessary  to  the  latter  pro- 
cess. The  investigations  of  Schmitz,  Strasburger7  and 
others  go  to  show,  however,  that  the  two  processes 
are  distinct,  and  that  the  nucleus,  instead  of  being 
related  to  cell  division,  holds  an  intimate  and  probably 
essential  relation  to  the  life  of  the  protoplasm. 

The  protoplasm  takes  on  another  form  in  the  chlor- 
ophyll bodies8  (see  fig.  9  c).  These  consist  of  a  proto- 

7  Zellbildung  und  Zelltheilung,  p.  371. 

8  Cf.    Strasburger,    Das    botanische    Practicum,   p.    350  ;     Schmiu, 
Chromatophoren  der  Algen. 


26  GREEN  SLIME. 

plasmic  body  containing  the  green  chlorophyll  pigment. 
The  surrounding  protoplasm  by  the  aid  of  the  chloro- 
phyll is  able  to  convert  inorganic  into  organized  matter, 
a  function  wanting  in  all  animals,  with  the  exception 
of  a  few  of  the  lowest,  like  Hydra  and  Euglena,  and 
also  wanting  in  some  plants,  e.  g.  fungi  and  colorless 
parasites. 

The  solid,  firm,  and  nearly  colorless  cell-wall  is  a 
product  of  the  protoplasm  consisting  essentially  of 
cellulose,  and  serves  as  a  protection  to  the  protoplasm. 
The  fine  granules  seen  in  the  protoplasm,  are  largely 
food  materials  produced  by  the  cell  in  excess  of  what 
the  present  needs  require. 

The  multiplication  of  the  plant  by  cell-division  is  a 
very  common  method  throughout  the  vegetable  king- 
dom.8 The  nucleus  first  disappears  and  two  nuclei  are 
formed  in  its  stead.  The  protoplasm  then  divides 
itself,  keeping  a  nucleus  in  each  part,  and  a  wall  is 
formed  between.  The  two  cells  thus  produced  soon 
attain  the  size  of  the  original  cell,  when  they  in  turn 
divide  into  two,  but  usually  by  a  partition  at  right 
angles  to  the  last,  and  so  on.  The  cells  thus  formed 
either  soon  become  separated,  or  retain  a  mechanical 
union. 

Another  method  of  multiplication  is  by  the  produc- 
tion of  zoospores.10  The  plastic  contents  of  a  cell, 
either  as  a  whole  or  divided  into  several  parts,  escapes 
from  the  cell  wall,  each  mass  pushes  out  a  pair  of 
delicate  protoplasmic  filaments  or  cilia,  which  moving 

9  Cf.    Bessey,  Botany,  p.  36,    for  a  statement  of  the  different  methods 
by  which  new  cells  are  formed. 

10  Cf.  Huxley  and  Martin,  Elementary  Biology,   p.    12,  15  ;    Howes, 
Atlas  of  Elementary  Biology,  p.  74,  pi.  xviii. 


PROTOCOCCUS  VIRIDIS.  27 

rapidly  back  and  forth  propel  the  naked  protoplasm 
through  the  water.  The  motion  and  form  give  a 
strong  resemblance  to  some  of  the  simplest  animals, 
hence  the  name  of  animal-like  spores.  After  a  time 
they  come  to  rest,  draw  in  the  cilia,  secrete  a  cell-wall, 
and  become  ordinary  Protococcus  cells.  Sometimes 
the  protoplasm  does  not  free  itself  from  the  cell  wall, 
but  contracts  somewhat,  the  cilia  are  protruded  through 
the  wall  and  the  mass  propelled  as  just  stated.  The 
production  of  zoospores  at  a  specified  time,  as  for  a 
class  demonstration,  is  attended  with  so  much  uncer- 
tainty that  their  study  has  been  omitted  from  the 
laboratory  work.  This  method  of  asexual  multiplica- 
tion will  be  studied  later  under  more  favorable  condi- 
tions in  Cystopus.11 

11  At  p.  47- 


DARK   GREEN    SCUM. 

Oscillaria  tennis  Ag. 

PRELIMINARY. 

THE  color  of  Oscillaria,  almost  any  species  of  which 
may  be  used,  is  generally  sufficient  to  enable  one  to 
distinguish  it  at  sight.  Its  dark  blue-green  is  in 
marked  contrast  with  the  yellow-green  of  most  other 
plants  which  form  scums.  It  is  very  common  on 
stagnant  water,  often  forming  patches  of  scum  thirty 
centimeters  (a  foot)  or  more  in  diameter,  which  becom- 
ing loaded  with  dust  finally  sink  to  the  bottom.  It  is 
also  very  common  about  watering  troughs,  along  street 
gutters,  at  the  outlet  of  drains,  on  wet  rocks,-  giving 
them  a  slippery  surface,  in  the  greenhouse,  and  especi- 
ally in  water  containing  a  small  amount  of  garbage. 
It  can  usually  be  grown  indefinitely  in  an  open  jar,  by 
supplying  the  water  as  it  evaporates,  or  with  less 
trouble,  when  once  established,  in  an  unstoppered  bottle, 
in  which  a  small  twig  or  flower  stem  of  some  sort  is 
inserted  to  provide  nutriment.  The  plants  are  often 
to  be  found  in  winter  in  as  good  condition  as  in  sum- 
mer. The  study  should  be  made  upon  growing  plants 
when  possible,  but  specimens  dried  on  paper  or  mica 
will  serve  quite  as  well,  except  to  show  the  oscillating 
movements,  which  are  characteristic  of  the  group  to 
which  Oscillaria  belongs. 


OSCILLARIA    TEN U IS.  29 

Only  the  following  material  is  necessary  for  the 
study:  fresh  plants,  or  in  their  absence  dried  speci- 
mens; a  dried  mass  half  as  large  as  a  pea;  and  alco- 
hol. 

LABORATORY  WORK. 

GROSS  ANATOMY. 

1.  Examine  a  small  mass  of  the  living  plant  which  has 
been  allowed  to  remain  undisturbed  for  several   hours 
in  a  watch-glass  of  water  ;  notice 

a.  The  deep  blue-green  color. 

b.  The     hair-like    unbranched    filaments,    radiating 
from  the  central  mass. 

2.  Sketch  the  plant  as  it  appears  in  the  watch-glass. 

3.  Mount  a  fragment  and  observe   the  uniform  diameter 
and  appearance  of  the  filaments. 

Pulverize  a  mass  of  the  plant  that  has  been  thoroughly 
dried,  place  in  a  test-tube  or  vial  with  nearly  twice 
the  bulk  of  water,  and  after  ten  to  twenty-four  hours 
notice 

4.  The  color  of  the  solution  when  seen  by  transmitted 
light  and  the  very  different  color  by  reflected  light, 
indicating  the  presence  of  phycocyanine. 

Pour  off  the  supernatant  water,  add  the  same  amount  of 

alcohol  instead,  and  after  an  hour  or  more  notice 

• 

5.  The    yellow-green   color    imparted     by     the    chloro- 
phyll. 

MINUTE  ANATOMY. 

A.  GENERAL  CHARACTERS.     Under    a  low 'power, 
notice 
i.    The  color. 


30  DARK  GREEN  SCUM. 

2.  The  numerous  filaments  of  uniform  diameter,  destitute 
of  branches. 

3.  Study  the  movements. 

B.    THE    INDIVIDUAL     FILAMENT.      Under    high 
power,  notice 

1.  The  structure  in  detail,  as  follows  : 

a.  The  rounded  extremities  of  uninjured  filaments. 

b.  The  outline  of  an  uninjured  apex,  whether  attenu- 
ated  or  not,  and  whether  bent   to   one   side   or 
straight. 

c.  The  delicate  lines  of  the  partition  walls  crossing 
the   filament    and    dividing    it    into    very    small 
cells. 

d.  The    comparative     length    and    breadth     of     the 
cells. 

e.  The  granular  contents,  and   their  distribution   in 
the  cell.1 

/.  The  delicate  colorless  sheath  to  be  seen  extending 
beyond  the  green  cells  at  some  torn  end  of  a  fila- 
ment, and  on  which  may  sometimes  be  detected 
transverse  lines  indicating  the  former  position  of 
the  end  walls  of  the  cells. 

2.  The  turgidity  of  the  cells:  notice  that 

a.  The  transverse  walls  in  an  uninjured  filament  are 
•plane,  while 

b.  The  last  cell  of  an  injured  filament  is  bulged   out- 
ward, making  the   outer  transverse  wall  convex, 
the  pressure  from   within  not   being   counterbal- 
anced from  without. 

3.  Draw  one  or  more  filaments. 

1  In  some  species  the  granules  are  collected  along  the  partition  walls. 


OSC ILL  ARIA   TEN  U IS.  .          31 

ANNOTATIONS. 

If  the  structure  of  Oscillaria  be  carefully  compared 
with  that  of  Protococcus  more  points  of  resemblance 
will  be  found  than  appear  at  first  sight.  New  cells  are 
formed  by  the  process  of  division,  as  in  Protococcus, 
but  the  partition  walls  are  always  parallel  and  in  one 
direction,  which  disposes  the  cell  families  in  filaments. 
The  individual  cells  have  thin  walls,  the  office  of  pro- 
tection being  relegated  to  the  sheath.  The  sheath, 
which  is  formed  from  the  outside  walls  of  the  cells  by 
a  modification  of  the  outer  portion,  is  a  structure  that  is 
mostly  confined  to  certain  groups  of  the  lower  plants, 
although  it  has  some  analogies  with  the  cuticle  of  the 
higher  plants.  The  protoplasm  is  homogeneous,  and 
not  differentiated  into  chlorophyll  bodies  and  nucleus 
as  in  Protococcus ;  chlorophyll  is,  however,  present, 
evenly  distributed  through  the  protoplasm,  but  no 
nucleus  has  yet  been  discovered.  The  study  of  the  pro- 
toplasm and  chlorophyll  is  much  obscured  by  the  pres- 
ence of  the  peculiar  coloring  matter,  phycocyanine, 
characteristic  of  the  Cyanophycece  to  which  Oscillaria 
belongs.  It  is  this  that  gives  the  deep  blue-green  color 
to  the  plants,  enabling  one  to  distinguish  them  at  sight. 
It  is  insoluble  in  alcohol,  but  soluble  in  water  when  the 
plants  are  dead,  while  chlorophyll  is  soluble  in  alcohol, 
but  not  in  water;  hence,  digesting  the  dead  plants  with 
water  removes  the  phycocyanine,  and  digesting  with 
alcohol  removes  the  chlorophyll.2  This  blue  color  is 
often  seen  on  the  sides  of  vessels  in  which  Oscillaria 
has  remained  so  long  as  to  die,  and  also  staining  the 
8  Cf.  Sachs,  Text-book  of  Botany,  2nd  Eng.  ed.,  p.  246,  766. 


32         .  DARK  GREEN  SCUM. 

herbarium  sheets  on  which  specimens  have  been 
dried. 

The  cells  are  assisted  in  keeping  together  by  the 
investing  sheath,  into  which  they  are  packed  like  a  roll 
of  lozenges  in  their  case.  This  structure,  together  with 
the  community  of  action  exhibited  in  producing  the 
peculiar  oscillating  and  nutating  movements,  makes  it 
evident  that  the  cells  of  each  filament  have  a  certain 
dependence  upon  each  other,  although  at  the  same 
time  each  is  capable  of  independent  existence.  It  may 
be  that  the  smallness  of  the  cells  and  the  thinness  of 
their  walls  is  in  some  way  correlated  to  this  unity  of 
function.  It  is  not  yet  definitely  known  how  the  move- 
ments in  Oscillaria  are  produced.3 

Turgidity  is  a  characteristic  of  living  cells.  It  is  the 
means  by  which  the  soft  parts  of  plants  are  enabled  to 
keep  their  form,  and  otherwise  to  serve  their  purpose. 
It  is  brought  about  by  the  strong  imbibition  power. of 
the  protoplasm,  causing  water  to  be  taken  up  until 
a  considerable  internal  pressure  is  created.4 

3  Engelmann  has  discussed  several  theories,  and  suggested   that   the 
movements  are  brought  about  by    vibratile  thread-like  extensions  of   the 
protoplasm  through  the  cell  walls.     Bot.  Zeit.  1879,  p.    49      According 
to  Hansgirg  it  is   due    to  an   osmotic  action    of   the   protoplasm.     Bot. 
Zeit.  1883,  p.  831. 

4  Cf.  Bessey,  Botany,  p.  166. 


COMMON  POND  SCUM. 

Spitogyra  quinina  Kiitz. 


PRELIMINARY. 

THE  members  of  this  genus  are  abundant  in  stagnant 
water  everywhere,  forming  bright  yellow-green  scums  of 
great  extent,  sometimes  diffused  beneath  the  surface,  or 
in  running  water  attached  to  stones.  They  may  be  read- 
ily distinguished  from  all  other  scum-producing  plants, 
except  from  a  few  of  their  close  allies,  in  having  a  slip- 
pery feel,  and  being  composed  of  long  unbranched  fila- 
ments, which  string  out  like  wet  hair  when  withdrawn 
from  the  water.  The  allied  kinds,  which  can  not  be 
separated  by  this  simple  test,  will  at  once  be  distin- 
guished when  placed  under  the  microscope  by  possess- 
ing no  spiral  chlorophyll  bands  as  in  Spirogyra.  When 
growing  vigorously  the  masses  of  Spirogyra  are  an 
intense  light  green  ;  when  beginning  to  fruit  they  turn 
brown,  and  look  very  uninviting  ;  but  as  the  characters 
which  distinguish  the  species  are  largely  drawn  from 
the  fruiting  condition,  the  collector  soon  learns  to 
regard  these  unsightly  objects  with  favor. 

The  vegetative  condition  may  be  found  at  any  time 
during  the  warmer  portion  of  the  year.  The  fruiting 
condition  occurs  from  early  spring  to  June  and  July, 
and  sparingly  during  the  remainder  of  the  warm  season. 

The  species  usually  grow  intermixed,  and  almost  any 


34  COMMON  POND  SCUM. 

gathering  will  answer  for  the  present  study,  as  5. 
longata  Vauch.,  S.  majuscula  Kiitz.,  and  similar  kinds 
have  been  kept  in  mind  as  well  as  5.  quinina  in  drawing 
up  the  outline  for  laboratory  work. 

Spirogyra  may  be  grown  in  the  laboratory,  and  the 
vegetative  condition  kept  always  at  hand,  by  using  a 
rather  deep  vessel  with  opaque  sides,  and  occasionally 
dropping  in  a  small  piece  of  peat  which  has  been 
thoroughly  boiled  and  afterward  saturated  with  the 
following  nutritive  solution:  1,000  cc.  of  water,  i  gm. 
potassic  nitrate,  .5  gm.  sodic  chloride,  .5  gm.  calcic  sul- 
phate, .5  gm.  magnesic  sulphate,  and  .5  gm.  finely  pul- 
verized calcic  phosphate.1  The  last,  for  which  burned 
bone  may  be  used,  is  only  sparingly  soluble.  If  run- 
ning water  can  be  conducted  through  the  jar  contain- 
ing Spirogyra,  so  that  the  water  in  it  may  be  slowly 
changed,  the  peat  and  nutritive  solution  can  be  dis- 
pensed with.  The  fruiting  plant  may  be  preserved 
in  fair  condition  for  study  in  a  fluid  of  equal  parts  of 
glycerine  and  alcohol. 

The  requisites  for  study  are  thrifty  growing  plants  ; 
fruiting  plants,  fresh  if  possible ;  alcohol ;  glycerine  ; 
and  iodine. 

LABORATORY    WORK. 
GROSS  ANATOMY. 

A.  GENERAL  CHARACTERS.     Notice 
i.    The  yellow-green  color  as  seen  in  mass. 

1  Sachs,  Vorlesungen  liber  Pflanzen-Physiologie,  p.  342. 


SPIROGYRA  QUININA.  35 

2.  The  slippery  feel,  when  the  plant  is  taken  between  the 
fingers. 

Float  a  small  amount  of  material  in  water  over  a  white 
surface,  and  observe 

3.  The   fine   unbranched  filaments  of   which   it   is  com- 
posed. 

4.  Their  uniform  diameter. 

5.  Their  length. 

Place  some  in  alcohol,  and  after  some  time  notice 

6.  The  color  imparted  to  the  alcohol  by  the  chlorophyll. 

B.  Mount  a  few  filaments,  and    notice  the  single  row  of 
alternating  light  and  dark  dots,  indicating  the  single  row 
of  cells.     This  can  not  be  seen  in  all  specimens. 

C.  THE  FRUITING  PLANT.     Mount  a  few  filaments 
from   a  fruiting  mass,  having  them  well  separated  on  the 
slide,  and  search  for 

i.  Paired  conjugating  filaments,  some  cells  of  which  are 
empty,  some  with  dark  colored  dots,  the  zygospores, 
and  a  few  often  remaining  unchanged  from  the  vege- 
tative condition. a 

MINUTE  ANATOMY. 

A.    GENERAL     CHARACTERS.      Under    low    power, 
notice 

i.  The  indefinite  length  ;  if  traced  to  the  end,  the  fila- 
ment will  probably  be  found  broken. 

5  The  presence  of  small  particles  of  dirt  and  other  debris  makes  it  diffi- 
cult to  distinguish  the  zygospores  and  conjugating  filaments  with  cer- 
tainty, and  it  is  always  best  to  verify  the  observation  with  the  compound 
microscope,  if  possible. 


3 6  COMMON  POND  SCUM. 

2.  The  uniform  diameter. 

3.  The  cell   contents ;  colorless,  except   the  conspicuous 
green  chlorophyll  bands. 

B.  THE    INDIVIDUAL    FILAMENT.      Using    a    high 
power,  notice 

1.  The  shape  of  the  cells. 

2.  Their  relative  length  and  breadth. 

3.  'Thz  cell  wall : 

a.  The  lateral  walls  j  parallel  and   without  markings 
of  any  sort. 

b.  The  end  walls  ;  at  right  angles  to  the  longitudinal 
axis,    and    plain    (unless    slightly   nodulated    or 
infolded,  which  occurs  in  a  few  species). 

4.  The  absence  of  any  visible  sheath,  although  the  pres- 
ence  of  at  least  a  thin  one  has  been  demonstrated  by 
the  slippery  feel. 

5.  The  cell  contents. 

a.      The  chlorophyll  bands,  taking  a  spiral  course  from 
one  end  of  the  cell  to  the  other,  passing  near  the 
periphery.     Note 
i.     The  number  in  each  cell.3 


3'When  a  cell  is  crowded  with  chlorophyll,  the  following  method  may 
be  used  to  advantage  in  determining  the  number  of  bands  :  count  the 
number  appearing  to  cross  the  band  ab,  between  the  point  a,  the  upper 
profile  view,  and  the  point  b,  the  lower  profile  view  ;  this  number  plus 

one  will  be  the 
number  re- 
quired. The 
diagram  shows 
a  cell  with  four 
bands  of  chlo- 
rophyll.— From 
Bot.  Gazette,  ix., 


SPIROGYRA  QUININA.  37 

ii.     The  number  of  turns  of  the  spiral. 

iii.  The  surface,  the  crenulated  and  wrinkled 
margin,  and  the  turned  up  edges  of  the 
band  forming  a  more  or  less  flattened  Y  m 
optical  section.  To  obtain  a  complete  con- 
ception of  these  particulars,  first  focus  upon 
the  peripheral  surface  of  the  band,  />.,  upon 
the  upper  (outer)  surface  of  the  part  nearest 
the  eye,  then  focus  upon  the  axial  (inner) 
surface,  and  finally  examine  the  profile  of  the 
band  seen  on  the  right  or  left  of  the  cell. 

iv.     The  nodules  at  varying  distances  along  the 
median  line  of  the  band.     Stain  with   iodine 
and  note 
a.      An    outer   ring  which   is   more    deeply 

colored,  starch,4  and 

ft.     A  central  light  spot,  pyrenoid.     Both  are 
best  seen  when  but  faintly  colored. 

v.  The  yellowish  brown  color  finally  imparted  to 
the  chlorophyll  band. 

b.  The  feeble  brownish  color  given  to  the  remainder 
oT    the    contents    of  the  cells,  deeper  along  the 
periphery. 

Run  under  glycerine  on  the  same  slide,  and  note 

c.  The  contraction  of  the  colored  protoplasmic  part, 
and  its  separation  from  the  cell  wall. 

d.  In  unstained  cells  presenting  the  least  obstruction 
from  the  chlorophyll  bands,  search  for  a  colorless 
irregular  body  with  radiating  arms,  near  the  center 
of  the  cell,  the  nucleus.    This  is  difficult  to  demon- 
strate in  some  species,  but  easily  seen  in  others. 


4  Unless  the  plants  have  been  in  sunlight  the  preceding  part  of  the  day 
the  test  for  starch  may  not  be  fully  successful. 


38  COMMON  POND  SCUM. 

e.  The   rounded,  usually   much   brighter   body   im- 
bedded in  the  nucleus,  and  occupying  a  consid- 
erable part  of  it,  the  nucleolus. 

f.  Draw  one  or  more  cells  showing  all  parts  noticed. 

6.  The  turgidity  of  the  cells,  shown  by  the  considerable 
convexity  of  the  last  end  wall  of  a  broken  filament, 
which  is  repeated  in  lessening  degree  by  the  walls  of 
successive  cells  until  a  point  is  reached  where  the  pres- 
sure on  opposite  sides  is  equal,  and  the  wall  remains 
plane.  Illustrate  with  a  sketch. 

C.  THE  FRUITING  PLANT.    Under  low  power,  notice 

1.  The  filaments  lying  side  by  side  in  pairs,  held  together 
by  conjugating  tubes. 

2.  The  irregular  outline  of   the   filaments,  caused  by  the 
uneven  lateral  expansion. 

3.  The  varying  character  of  the  contents  of  the  cells  :  some 
with  distinct  bands  of  chlorophyll  ;  some  with   a  con- 
fused green  mass  ;  some  with  green  or  brown  rounded 
bodies  of  definite  shape,  the  zygospores ;  some  empty. 

Under  high  power,  notice 

4.  The  general  shape  of  the  cells  as  influenced  by  the  cell 
contents. 

5.  The  conjugating  tube  :  note 

a.  The  enlargement  at  the  middle,  where  an  indenta- 
tion marks  the  line  of  union  of  the  two   originally 
separate  portions. 

b.  In  some  cells  which  have  not  yet  conjugated,  a 
greater  or  less  protuberance  on  the  side  next  the 
accompanying  filament  ;  the  beginning  of  a  con- 
jugating tube. 

6.  The  cell  contents. 


SPIROGYRA  QUIN1NA.  39 

a.  By  studying  various  specimens,  trace  the  changes 
from  the  vegetative  condition,  through  the  several 
stages  of  disintegration  of  the   chlorophyll  band 
and  contraction  of  the  protoplasm  to  the  forma- 
tion of  a  rounded  uniformly  greenish-brown  mass  ; 
noticing  at  the  same  time,  that  this  change  takes 
place  side  by  side  with  the  formation  of  the  conju- 
gating tube.     In  general  all  the  stages  are  easily 
found. 

b.  Where  the  conjugating  tube  is  fully  formed,  note 
that  one  cell  is  empty,  and  the  connected  cell  con- 
tains a  single  mass,    the  spore  produced  by  the 
conjugation. 

7.  The  mature  zygosporc  :  note 

a.  The  shape  and  color. 

b.  The  contents. 

c.  The  wall  of  greater   or   less   thickness,   usually 
resolvable  into  two  or  more   layers   of   different 
colors. 

8.  Make  drawings  to  illustrate  the  parts  and  changes  of 
the  fruiting  filaments. 

ANNOTATIONS. 

In  the  form  and  manner  of  growth  of  Spirogyra,  we 
meet  with  no  features  not  seen  in  Oscillaria  or  Proto- 
coccus,  except  the  arrangement  of  the  protoplasm  and 
chlorophyll  bodies.  The  filaments  are  built  on  the 
plan  of  Oscillaria,  with  the  cells  larger,  and  the  sheath 
so  much  reduced  that  it  can  be  demonstrated  only  with 
difficulty.  In  some  species  of  the  closely  related  genus 
Zygnema,  however,  the  sheath  is  readily  discernible. 
The  increase  in  the  number  of  cells  is  effected  in  the 


40  COMMON  POND  SCUM. 

same  manner  as  in  Oscillaria,  i.  e.  by  the  division  of 
the  cell  into  halves  by  a  transverse  partition  always  in  the 
same  direction,  with  subsequent  expansion  of  the  new 
cells. 

The  disposition  of  the  protoplasm  shows  a  marked 
advancement  over  the  lower  plants.  Instead  of  being 
diffused  evenly  through  the  cell,  it  forms  a  layer  lining 
the  cell-wall,  known  to  older  botanists  as  the  primor- 
dial utricle,6  while  it  only  partly  occupies  the  central 
portion  of  the  cell.  The  remaining  space  is  rilled  by 
the  cell-sap,  which  consists  of  water  holding  various 
substances  in  solution.  The  nucleus  and  nucleolus, 
particularly  the  latter,  are  remarkably  large.  In  the 
chlorophyll  band  we  have  a  unique  feature ;  for  while 
it  is  common  to  have  the  chlorophyll  separated  in  well 
defined  bodies,  it  is  only  in  Spirogyra  and  its  close  rela- 
tives that  it  assumes  such  peculiar  and  beautiful  shapes. 

The  presence  of  starch  granules  in  the  chlorophyll 
bodies  is  a  very  significant  fact  in  the  physiological 
study  of  plants.  They,  or  very  similar  substances, 
are  the  first  products  of  assimilation,"  being  the  material 
from  which  the  elaborate  frame-work  of  the  plant  is 
eventually  constructed.  Usually  the  starch  when  first 
formed  is  scattered  irregularly  through  the  chlorophyll 
bodies ;  in  Spirogyra,  however,  the  principal  part  is 
collected  in  a  layer  of  granules  about  definite  centers 
forming  hollow  spheres.  Within  these  spheres  is  a 
highly  refractive  protoplasmic  body,  the  pyrenoid. 

5  So  named  by  H.  v.  Mohl,  Bot.  Zeit,  1844,  p.  273  ;  The  Vegetable 
Cell,  p.  36- 

6  Cf.  Sachs ,  Handbuch  d.  Exper.-Phys.,  p.  307  ;  Textbook  of  Botany, 
2nd  Eng.  ed.,  p.  703  ;     Bessey,  Botany,  p.    178. 


SPIROGYRA   QUININA.  41 

The  starch  is  imbedded  in  the  chlorophyll  bodies,  and 
is  quite  distinct  from  the  pyrenoid,  although  the  con- 
stancy in  the  relative  position  of  the  two  would  indi- 
cate some  connecting  influence.  The  pyrenoids  have 
been  long  known  and  variously  interpreted,7  but  the 
recent  careful  studies  of  Schmitz8  show  that  they  are 
quite  analogous  to  nucleoli,  especially  in  chemical 
constitution  and  mode  of  multiplication.  They  are 
only  found  in  some  of  the  algae  and  in  a  few  higher 
plants. 

It  is  when  we  examine  the  fruiting  of  Spirogyra, 
that  its  great  advancement  beyond  the  simple  forms 
of  the  protophytes  becomes  apparent.  We  meet  at 
once  with  a  true  sexual  process,  which  although  very 
simple  is  yet  clearly  defined  and  easily  traced.  This 
process,  as  indeed  in  all  other  instances  however  mod- 
ified, consists  essentially  of  the  intimate  union  of  the 
protoplasm  (especially  of  the  nucleus9)  of  one  cell  with 
that  of  another,  which  after  a  longer  or  shorter  period 
results  in  the  production  of  a  new  individual.  Usually 
in  higher  groups  there  is  a  marked  difference  in  size, 
and  we  may  conclude  in  other  less  apparent  respects, 
between  the  protoplasm  which  is  fertilized,  the  female 
element,  and  the  protoplasm  which  fertilizes  it,  the 
male  element.  In  Spirogyra  a  slight  difference  between 
the  two  elements,  especially  in  size,  has  been  pointed 
out  by  DeBary,10  Wittrock,"  and  more  fully  by  Ben- 

7  Hofmeisterin  Die  Lehre  von  der   Pfianzenzelle  (1867),  p.  370,  calls 
them  vacuoles. 

8  Die  Chromatophoren  der  Algen  (1882),  p.    37  etseq.  ;  Quart.  Jour. 
Micr.  Sci. ,  xxiv,  p.  246. 

9  Cf.  Strasburger,  Neue  Untersuchungen,  p.  80. 
10Untersuchungen  Uber  die  Familie  der  Conjugaten,  1858,  p.  4. 
"Quart.  Jour.  Micr.  Sci.,  1873,  p.  123. 


42  COMMON  POND  SCUM. 

nett.18  According  to  Bessey,"  however,  we  should 
consider  this  case  the  simplest  kind  of  sexuality,  in 
which  there  is  as  yet  no  differentiation  into  proper 
male  and  female.  For  the  further  discussion  of  sexu- 
ality in  plants,  the  student  is  referred  to  the  writings 
of  Pringsheim,14  Sachs,"  Ward,16  Strasburger,17  and 
others. 

The  two  plants  previously  examined  may  be  found 
in  any  month  of  the  year,  but  the  one  now  under 
examination  dies,  and  entirely  disappears  from  sight 
by  the  time  winter  has  fairly  set  in.  It  is  reproduced 
the  coming  spring  by  the  germination  of  the  zygospores, 
which  lie  at  the  bottom  of  the  water  during  the 
winter.  These  resting  spores  are  admirably  fitted  for 
spanning  this  unfavorable  season  for  vegetation.  As  a 
rule  they  require  a  long  period  of  rest  before  reaching 
the  germinating  condition,  so  that  while  they  are 
formed  in  the  earlier  part  of  the  warm  season,  it  is 
usually  not  till  the  following  spring  that  they  show  a 
disposition  to  grow ;  they  are  dense  and  heavy,  and 
therefore  sink  to  the  bottom  as  soon  as  set  free  by  the 
decomposition  of  the  filaments  in  which  they  grew  ; 
and  lastly,  their  thick  double  or  triple  covering  serves 
as  an  ample  protection  to  the  living  protoplasm  with- 
in. 

12  Jour.   Linn.  Soc.,  xx  (1884),  p.  430;  Amer.  Nat.,  xvii  (1884),  p.  421. 

13  Amer.  Nat.,  xix  (1885),  p.  995. 

14  Monatsber.  d.   k.   Akad.  der  Wiss.  in  Berlin,  1869. 
16  Textbook  of  Botany,  2nd  Eng.   ed.,  p.  986. 

16  Quart.  Jour.  Micr.  Sci.,  1884,  p.  262. 
"  Op.  cit. 


WHITE     RUST. 

Cystopus  candidus  Lev. 


PRELIMINARY. 

THIS  isavery  common  parasitic  fungus,  forming  white 
patches  on  the  surface  of  the  leaves,  stems  and  flowers 
of  many  cruciferous  plants,  such  as  various  species  of 
Capsclla,  Sisymbrium,  Lcpidium,  Nasturtium,  Sinapis, 
and  Raphanus.  It  is  especially  abundant  upon  Cap- 
sella  or  shepherd's  purse,1  from  early  spring  till  late 
in  the  fall,  whitening  and  distorting  the  stems,  leaves 
and  flowers.  Yet,  notwithstanding  such  luxuriant 
growth,  the  sexual  condition  with  resting  spores  is  not 
abundantly  found  on  this  host,  but  is,  however, 
produced  in  great  luxuriance  inside  the  flowers  and 
flowering  branches  of  radish  (Raphanus),  causing 
them  to  become  enormously  enlarged,  sometimes  even 
two  to  five  centimeters  (one  or  two  inches)  across  (see 

fig-  3). 

It  is  possible,  with  patience  and  care,  to  make  out 
the  parts  without  the  use  of  chlor-iodide  of  zinc,  but  it 
affords  so  much  assistance  that  it  ought  to  be  used  if 
obtainable. 

The  requisites  for  the  following  study  are  branches 

1  Fora  description  of  shepherd's  purse  see  p.  222. 


44  WHITE  RUST. 

of  Capsella  bearing  the  rust,  dried  or  fresh ;  the  same, 
together  with  some  young  terminal  portions  of  affected 
branches,  preserved  in  alcohol ;  the  swollen  flowers  of 
radish  or  Capsella  taken  when  not  too  young,  but  still 
tender  and  brittle,  preserved  in  alcohol ;  freshly  gath- 
ered branches  of  rusted  Capsella,  or  some  which  have 
not  been  gathered  more  than  twenty-four  hours  and 
kept  in  a  moist  bell  jar;  chlor-iodide  of  zinc;  potassic 
hydrate ;  and  iodine. 

LABORATORY    WORK. 
GROSS  ANATOMY. 

1.  The  vegetative  body  of  the  plant  consists  of  delicate 
transparent  threads,  ramifying  through  the  tissues  of 
the  host  on  which  it  grows,  and  can  not  be  detected 
without  the  aid  of  the  compound  microscope. 

2.  The  sort  :  in  a  fresh  or  dried  specimen  notice 

a.  The  white  blister-like  pustules  on  the  surface  of 
the  host,  son  ;  shape  and  extent. 

b.  The  thin  external  membrane,   at  first  entire,   then 
becoming  ruptured  in  the  middle. 

c.  The  white  powdery  spores,  conidia,  which  drop 
out  upon  jarring,  if  the  specimen  is  dry. 

3.  Mount  a  section  from  an  alcoholic  specimen  of  radish 
flower  containing  Cystopus,  stain  with  chlor-iodide  of 
zinc,  and  notice 

a.  The  numerous  dots  scattered  through  the  tissue 
of  the  radish,  the  oospores  or  resting  spores.  The 
staining  shows  them  as  red  dots  lying  in  a  blue  or 
yellow  ground  tissue. 


C  YS TOP  US  CA  NDID  i  '.s.  45 

MINUTE  ANATOMY. 

Mount  a  transverse  section  of  an  alcoholic  specimen  of  a 
stem  or  leaf  bearing  Cystopus,  and  under  low  power 
notice 

1.  A    layer  of    short   vertical   filaments,   conidiophores," 
together  forming  the  hymenium,  which  appear  to  arise 
from  the  tissues  of  the  host  and  bear  on  their   free 
extremities 

2.  Chains  of  rounded  conidia,  now  mostly  detached. 

The  vegetative  portion  of  the  plant,  consisting  of  branch- 
ing filaments  pervading  the  tissues  of  the  host,  can  rarely 
be  made  out  even  after  staining,  without  specially  skillful 
manipulation. 

3.  The  everted  membrane  formed  from  the  surface  cells  of 
the  host,  formerly  covering  the  sorus. 

4.  Draw. 

Under  high  power  notice 

5.  The  conidia  :  exact  shape,  wall  and  contents. 

6.  The  delicate  neck  or  pedicel  supporting  each  conidium 
before  becoming  detached. 

7.  Draw  a  conidiophore  with  its  conidia. 

Take  a  piece  of  the  host  bearing  conidia  and  boil  for  a 
minute  or  two  in  potassic  hydrate  ;  remove  a  portion  to  the 
slide,  tease  apart  thoroughly  with  needles,  and  stain  with 
chlor-iodide  of  zinc.  Notice 

8.  Much    branched,    often  matted   filaments,   mycelium, 
pulled  out  from  the  tissues  of  the  host. 

2  Cf .  fig.  8. 


46  WHITE  RUST. 

a.  The  irregular  thickness  of  the  mycelial  filaments, 
or  hyphae.3 

b.  The  absence  of  transverse  partition  walls. 

c.  Draw  a  few  hyphae. 

9.    The  groups  of  conidiophores. 

a.  The    manner   in    which   the   conidiophores   arise 
from  the  vegetative  hyphae. 

b.  The    successive    degrees    of   abstriction   of    the 
conidiophores  resulting  in  the   formation   of   the 
spores. 

c.  Draw  a  group  of  conidiophores  with  the  attached 
hyphae. 

Prepare  a  slide  as  before,  using  the  immature  terminal 
part  of  the  branch  bearing  the  Cystopus,  preferably  a 
flowering  branch  ;  search  among  the  untorn  tissues  of  the 
youngest  organs,  particularly  in  the  pedicels  of  the  young 
buds,  for  the  extremities  of  the  advancing  hyphae.4 
After  noting  the  more  direct  course  of  the  hyphae,  and  the 
fewer  branches,  observe 

10.  Very  small  globular  bodies  lying  along  the  side  of  the 
hyphae,  haustoria  or  sucking  organs.5  They  usually 
appear  brighter  than  the  hyphae,  and  are  quite  abund- 
ant. If  the  illumination  is  sufficiently  strong,  observe 

a.  The  very  delicate  stalks  by  which  the  haustoria 
are  connected  with  the  hyphae. 

b.  Draw  some  hyphae  with  haustoria. 


*Hypha  is  the  name  applied  to  a  single  filament,  while  mycelium  is  a  col- 
lective term  for  a  number  of  hyphae. 

4  If  properly  stained  there  will  be  no  difficulty  in  distinguishing  the 
mycelium  from  the  tissues  of  the  host. 

6  It  is  difficult  to  demonstrate  these  without  proper  staining. 


CY STOP  US  CANDID  US.  47 

Dust  some  conidia  from  a  fresh  growing  plant8  upon  a 
slide  and  mount  with  water  ;7    in  about  an  hour,  notice 

11.  The  small  protuberance  formed  on  one  side  of  some  of 
the  conidia,  which  opens  and   permits  the  escape  of 
the  protoplasm  in  the  form  of  several  motile  bodies, 
zoospores, 

a.  The    shape   of    the    zoospores,  and    the   pair   of 
bright  spots  in  each. 

b.  Study  the  increment. 

c.  Notice   the    pair   of    delicate  vibratile   cilia,    by 
means  of  which  the  movements  are  effected.  Stain 
with  iodine,  and  the  cilia  can  be  seen  more  easily. 
Note  their  length. 

d.  The  color  imparted  to  the  zoospore  and  its  cilia  by 
the  iodine. 

<?.  Draw  some  zoospores,  and  also  one  or  two  conidia 
which  have  not  discharged  zoospores,  and  one  or 
two  empty  ones. 

12.  The  sexual  reproduction.     Stain  a  section  of  an  alco- 
holic specimen  of  radish  flower  containing  oospores 
with  chlor-iodide  of  zinc,  and  notice 

a.  The  numerous  globular  bodies,  stained  wine-red, 
lying  in  the  tissues  of  the  radish,  oogonia. 

b.  Accompanying  them,  and  stained  the  same,  smaller 
rounded  bodies,  antheridia. 

c.  In    some    of    the  oogonia,    a    globular   mass   of 
granular   protoplasm,    not  completely   filling   the 
oogonium,  the  oosphere. 

d.  A  slender  tube  passing  from  the  antheridium  to 

6  The  conidia  will  germinate  if  sown  at  any  time  of  day,  provided  the 
specimens  are  fresh,  but  will  do  so  more  readily  when  sown  in  the  morn- 
ing from  plants  which  have  remained  over  night  under  a  moist  bell  jar. 

7  Care  must  be  taken  that  the  water  does  not  evaporate,  and  to  guard 
against  this  it  is  best  to  use  a  slide  having  a  shallow  cell. 


48  WHITE  RUST. 

the    oosphere,  the  fertilizing  tube  ;  very  difficult 
to  demonstrate.     Draw. 

e.      In  older  oogonia,  more  opaque  roughened  bodies 
the  oospores,   formed  from  the  oospheres.     Note 
i.     The  flexuous  ridges  on  the  exterior, 
ii.     The  contents,  in  spores  not  too  mature. 
/.      Draw  some  oogonia  and  accompanying  antheridia 
showing  different  stages  of  development   of   the 
oosphere  and  oospore. 

Tease  out  some  tissue  containing  oospores,  which  has 
been  boiled  in  potassic  hydrate,  stain  lightly  or  not  at  all, 
and  notice 

g.    The  manner  in  which  the  oogonia  and  antheridia  arise 

from  the  vegetative  hyphae.  Draw  a  few  examples. 

//.      The  rather  strong,   pointed  beak  sometimes  to  be 

seen  on  one  side  the  antheridium,  the  fertilizing  tube 

which  has  been  pulled  out  of  an.oogonium.    Draw. 

ANNOTATIONS. 

In  Cystopus  we  have  a  much  simplified  condition  of 
an  advanced  type  of  development.  The  higher  devel- 
opment is  shown  in  its  sexual  reproductive  apparatus, 
the  sexual  elements  being  quite  dissimilar  in  size  and 
in  behavior.  The  larger  (female)  element,  the  oogo- 
nium,  receives  the  protoplasm  of  the  smaller  (male) 
element,  the  antheridium,  the  former  remaining  in  a 
passive  state,  while  the  antheridium  is  the  active  agent 
in  securing  the  union.  This  is  the  essential  plan  for 
all  higher  plants,  as  well  as  for  the  group  to  which 
Cystopus  belongs,  the  Oophyta.8  The  transfer  of  the 

8  The  terms  Zygophyta,  Oophyta  and  Carpophyta  are  used  for  the 
three  great  groups  of  lower  plants,  in  accordance  with  the  suggestion  of 
Prof.  C.  E.  Bessey  in  the  American  Naturalist,  xvi  (1882),  p.  46, 
and  first  introduced  in  his  Essentials  of  Botany,  1884. 


CY STOP  US  CANDID  US.  49 

protoplasm  by  means  of  a  fertilizing  tube,  and  the 
subsequent  formation  of  a  thick-walled  resting  spore  is 
very  similar  to  what  takes  place  in  Spirogyra.  In  both 
cases  the  spore  clothes  itself  with  a  thin  inner  wall, 
very  difficult  to  see  clearly,  and  an  outer,  thick  pro- 
tective wall.  In  Cystopus  this  outer  wall  is  sculptured 
in  a  manner  characteristic  of  the  species.  The  oospores 
thus  formed  remain  over  winter  ;  the  tissues  in  which 
they  lie  become  disintegrated  ;  they  are  distributed  by 
rain' and  wind,  and  finally  germinate. 

Next  to  the  mode  of  sexual  reproduction,  the  most 
interesting  feature  about  the  plant  under  consideration 
is  its  habit  of  life  and  the  adaptations  which  have  been 
induced  thereby.  It  is  throughout  its  existence  a 
complete  parasite,  growing  and  feeding  upon  plants  of 
a  very  high  degree  of  organization.  Being  no  longer 
required  to  elaborate  food  for  itself,  finding  it  always 
at  hand  and  of  superior  quality,  it  possesses  no  chlo- 
rophyll bodies  by  which  it  might  assimilate  its  own 
food,  and  is  therefore  quite  colorless.  As  it  grows, 
it  sends  its  branching  filaments  ramifying  throughout 
all  the  softer  tissues  of  the  host.  They  do  not 
penetrate  the  cells,  however,  but  push  about  between 
them,  and  in  order  to  extract  the  nourishing  fluids 
readily,  especially  in  the  newest  portions  where  rapid 
growth  is  taking  place,  send  out  sucking  tubes  or 
haustoria,  which  penetrating  the  adjacent  cells  expand 
into  minute  absorbing  bulbs. 

The  means  of  distribution  which  the  plant  possesses 
in  its  oospores  is  rather  limited,  being  inferior  to  that 
of  Spirogyra  ;  and  when  once  established  in  a  host  it 
is  debarred  from  all  further  locomotion,  such  as  the 


50  WHITE  RUST. 

moving  water  imparts  to  the  spores  of  Spirogyra.  In 
order  to  secure  certain  and  extensive  distribution,  there- 
fore, and  to  provide  for  a  succession  of  crops  through  the 
growing  season,  it  produces  conidia  or  summer  spores 
in  the  greatest  profusion,  which  being  light  and  dry 
are  easily  blown  about  by  the  wind,  and  are  ready  to 
germinate  at  once.  The  thin  wall  and  active  pro- 
toplasm of  the  conidia,  from  which  they  derive  this 
advantage,  render  them  at  the  same  time  short  lived, 
so  that  if  a  conidium  does  not  find  favorable  con- 
ditions for  growth  within  a  few  hours  after  reaching 
maturity,  it  perishes.  The  conidia  germinate  in  water, 
and  with  best  results  in  a  film  of  water,  such  as  is 
formed  by  heavy  dew.  To  still  further  promote  dis- 
tribution, each  conidium  breaks  up  into  several  active 
zoospores,  which,  after  moving  about  for  fifteen  min- 
utes or  so  and  finally  coming  to  rest,  put  out  a  myce- 
Hal  tube  that  penetrates  the  host,  and  forms  a  new 
plant.  The  zoospores,  except  in  being  colorless  like 
the  parent,  remind  us  of  those  of  Protococcus,  serving 
the  same  purpose  of  distribution  and  reproduction. 

The  absence  of  septa,  except  for  the  separation  of 
the  antheridia,  oogonia  and  conidia,  making  the  vege- 
tative portion  a  continuous  cavity,  is  a  character 
shared  with  many  other  members  of  theOophyta,  both 
colorless  and  green  forms,  and  with  some  of  the  molds 
belonging  to  the  Zygophyta. 

The  student  has  doubtless  been  struck  with  the 
rarity  of  the  cases  in  which  he  could  detect  a  fertilizing 
tube,  even  where  the  antheridium  appeared  to  lie  in 
the  proper  plane.  There  is  doubtless  a  reason  for  this 
aside  from  the  mere  difficulty  of  manipulation,  which 


CYSTOPUS  CANDID  US.  51 

is  to  be  sought  in  the  nature  of  the  parasitism  exhibited 
by  Cystopus.  Whatever  may  be  the  full  significance 
of  sexuality,  many  facts  point  to  the  belief  that  it  is 
an  expedient  for  the  reinvigoration  of  the  exhausted 
energies  of  the  plant.9  Cystopus  is  intimately  asso- 
ciated with  a  plant  immensely  above  it  in  the  scale  of 
development  and  of  a  correspondingly  higher  poten- 
tiality. Its  vigor  is  in  direct  ratio  to  that  of  its  host, 
which  latter  far  exceeds  the  requirements  of  the  simple 
parasite.  The  energy  which  the  parasite  receives 
from  its  host  may  take  the  place  to  some  extent  of  that 
usually  obtained  through  the  sexual  process.  It  there- 
fore seems  justifiable  to  believe  that  while  the  anther- 
idia  are  in  most  cases  formed,  the  fertilizing  tube  is 
often  either  not  present  or  functionless,  i.  e.  that  we 
have  the  production  of  oospores  without  the  aid  of  the 
male  element,  a  method  known  as  parthenogenesis,10  a 
difficult  matter  to  establish  by  observation.  This  view 
is  rendered  more  probable  by  the  fact  that  it  is  the 
customary  mode  of  reproduction  in  some  of  the  closely 
allied  Saprolegniae  "  which  are  mostly  parasitic  for  at 
least  a  part  of  their  life  upon  insects,  a  still  more 
highly  organized  food  than  that  obtained  by  Cystopus 
and  its  immediate  allies. 

9  Ward,  Quart.  Jour.  Micr.   Sci.  xxiv,   (1884),  p.  303;  Bot.   Gaz.  ix, 
p.  146. 

10  Sachs,  Text-book  of  Botany,  2nd  Eng.  ed.,  p.  902  ;  Ward,  1.  c.,  p. 
307. 

11  Pringsheim    in   Jahrb.     f.    Wiss.  Bot.,    ix  ;  DeBary,    Beitrage   zur 
Morph.  u.  Phys.  der  Pilze,  4te  Reihe,  p.  73  ;  Sachs,  1.  c.,  p.  275. 


THE  LILAC  MILDEW. 
Microsphcera  Friesii  Lev. 

PRELIMINARY. 

THE  mildew  on  lilac  is  extremely  common  in  the 
United  States,  making  the  upper  surface  of  the  leaves 
look  white  and  moldy  from  midsummer  on.  The 
first  stage  at  which  the  fungus  is  ready  to  gather  is 
when  it  appears  powdery,  which  is  usually  in  June  or 
July,  the  earlier  collections  being  the  best.  The  next 
gathering  should  be  made  in  the  early  part  of  Septem- 
ber, and  another  just  before  the  leaves  fall.  As  the 
leaves  bearing  the  fungus  are  gathered,  lay  them  in  a 
book  or  plant-press  to  dry.  If  it  is  possible  to  examine 
the  first  stage  with  fresh  material  it  will  prove  more 
satisfactory,  but  for  the  remainder  dried  material  will 
answer  quite  as  well. 

The  required  material  consists  of  dried  lilac  leaves 
bearing  the  fungus,  gathered  in  midsummer  and 
autumn  ;  and  potassic  hydrate. 

LABORATORY  WORK. 

GROSS  ANATOMY. 

A.  GENERAL  CHARACTERS.     Notice 

i.    The  distribution  of  the  fungus  over  the  surface  of  the 
leaf. 


MICROSPH&RA  FRIESII.  53 

2.    The  color. 

B.  THE  CONIDIA.     Notice 

i.    The  pulverulent  appearance  on  the  leaves  first  gathered, 
caused  by  the  abundant  conidia. 

C.  THE  FRUIT.     Notice 

1.  The  black  dots  on  leaves  gathered  later  in  the  season, 
the  spore-fruits  or  perithecia. 

2.  Associated  with  the  black  dots,  other  yellow  ones,  the 
immature  fruits. 

MINUTE  ANATOMY. 

A.  THE  MYCELIUM.     Scrape  the  fungus  from  the  sur- 
face of    a    leaf  gathered  in   early    summer,    having    first 
moistened  it  with   potassic  hydrate  if  the   specimen  is  a 
dried  one,  and  under  high  power  notice 

1.  The  colorless  filaments  of  the  mycelium. 

a.  The  branching. 

b.  The  irregular  diameter. 

c.  The  rarity  of  partition  walls. 

2.  Small   lateral  expansions   of   the  filaments,  haustoria, 
somewhat    like   irregularly  indented  disks  with    very 
short  thick  stalks.     Generally  difficult  to  find. 

3.  Draw. 

B.  THE  CONIDIA.     Prepare  a  slide  as  before  from  a  pul- 
verulent surface,  and  notice 

1.  The  abundant  conidia,  separated  and  free,  owing  to  the 
manipulation. 

a.  Their  shape  and  color. 

b.  The  cell-wall  and  contents. 

2.  The  conidia-beartng  branches,   or  conidiophores,  which 
leave   the  mycelial    filaments  at  right  angles,  and  are 
provided  with  cross  partitions  at  regular  intervals,  and 


54  LTLAC  MTLDP.W. 

to   which   may    yet    be    attached  some  fully  formed 
spores. 

3.    Draw  some  conidiophores  and  conidia. 

C.  THE  PERITHECIA.     Prepare  a  slide  as  before  with 
mature  fruit,  and  notice 

1.  The  shape  and  color. 

2.  The   reticulations  of   the   surface   due   to  the  cellular 
structure. 

3.  The  appendages  extending  out  from  the  sides.     Note 

a.  The  number. 

b.  The  color. 

c.  The   length   compared  with   the    diameter   of  the 
perithecium. 

d.  The  cross  partitions,  if  any. 

e.  The  manner  of  branching,  and  the  number  of  times 
in  each. 

4.  Draw  a  perithecium  with  its  appendages. 

Crush  the  perithecia  while  watching  them  through  the 
instrument,  by  pressing  on  the  cover-glass  with  a  dis- 
secting needle,  and  notice 

5.  The  escape  of  sacs  containing  spores,  asci.     Note 

a.  The  number  from  each  perithecium. 

b.  The  general  shape. 

c.  The   short  pedicel  or   beak   by   which  they    were 
attached. 

d.  The  thin  part  of  the  wall  at  the  apex,  not  to  be 
seen  in  every  case. 

e.  The  number  of  spores  (ascospores)  in  each  ;  their 
shape. 

/.      Draw  an  ascus  with  its  spores. 


MICROSPHMRA  FRIESII.  55 

6.    Examine  younger  and  younger  perithecia  to  as  early  a 
stage  as  possible.     Draw. 

D.  The   very   simple    ORGANS  OF  FERTILIZATION, 

the   beginning  of  the   perithecia,  can  rarely  be  found1  ;  if 
seen,  notice 

a.  The  larger  axial  cell,  the  carpogonium. 

b.  The  smaller  lateral  cell,  applied  closely  to  the  car- 
pogonium, the  antheridium. 

^.       Draw. 

ANNOTATIONS. 

The  group  of  Carpophyta  to  which  Microsphaera 
belongs,  a  very  large  one,  is  characterized  by  having  a 
special  covering  for  the  spores,  developed  as  a  result  of 
fertilization.  Except  in  some  of  the  higher  forms,  the 
fertilization  takes  place  much  as  in  the  Oophyta,  but  the 
subsequent  development  is  very  different,  for  an  out- 
growth of  branches  from  the  portion  immediately 
below  the  organs  of  fertilization  at  once  arises  which 
eventually  envelops  the  forming  spores  and  develops 
into  the  body  of  the  fruit. 

It  is  altogether  likely  that  Microsphaera  has  reached 
an  advanced  parthenogenetic  stage,  i.  e.  the  fruits  are 
largely  produced  without  the  transfer  of  protoplasm 
from  the  antheridium  to  the  carpogonium,  which  consti- 
tutes fertilization.  On  this  account  some  other  plants 
better  illustrate  the  fertilization  and  the  early  growth  of 
the  fruits  than  the  one  used  ;  the  student  is  advised 
to  examine  these  features,  if  possible,  in  Nemalion,  one 

1  To  get  some  idea  of  their  shape,  examine  figs.  188  and  189  in  Bessey's 
Botany,  p.  280-1. 


5  6  LI  LA  C  MILDE  W. 

of  the  marine  algae,  or  Batrachospermum,  one  of  the 
fresh-water  algae. 

The  comparison  of  Microsphaera  with  Cystopus  is 
very  instructive  in  showing  how  practically  the  same 
ends  have  been  reached  by  widely  different  plants. 
Both  are  parasitic,  the  one  living  inside  the  host,  the 
other  upon  its  surface,  both  deriving  nourishment  by 
means  of  haustoria,  in  addition  to  what  is  absorbed 
directly  through  the  walls  of  the  filaments.  It  is  some- 
what doubtful,  however,  if  the  haustoria  of  Micro- 
sphaera pierce  the  cells  of  its  host,  although  those  of 
some  closely  related  species  are  thought  to  do  so.2 
Both  bear  aerial  asexual  spores,  which  are  formed 
by  successive  abstrictions  from  vertical  mycelial 
threads,  the  main  difference  being  that  in  Cys- 
topus these  must  break  through  the  surface  tis- 
sue of  the  host,  and  are  therefore  required  to  grow  in 
groups  in  order  to  exert  the  necessary  force,  while  in 
the  superficial  Microsphaera  they  are  single,  and  evenly 
distributed.  The  conidia  of  Cystopus  germinate  by 
formation  of  zoospores,  while  those  of  Microsphaera 
grow  a  mycelial  filament  at  once,  a  difference  due  to 
some  obscure  cause.  Both  plants  form  resting  spores, 
but  in  Cystopus  the  protective  covering  is  the  thick- 
ened wall  of  the  spore,  in  Microsphaera  it  is  a  specially 
developed  shell,  inclosing  a  number  of  spores  in  sacs. 

There  is  not  much  known  of  the  manner  in  which 
these  fruits  pass  the  winter  and  give  rise  in  the  spring 
to  another  growth  of  mildew.3  It  is  plain  f«-om 

3  Cf.  Bessey,  Botany,  p.  279. 

3  Wolff  has  studied  the  germination  of  the  ascospores  in  Erysiphe. 
graminis.  Bot.  Zeit.  1874,  p.  183, 


MICROSPH&RA  FRIESII.  57 

the  structure,  however,  that  the  spores  escape  from  the 
sacs  through  the  thin  spot  at  their  apex,  but  not  so 
evident  how  they  escape  from  the  shell  of  the  fruit 
and  reach  the  host  plant.  The  appendages  we 
may  suppose  are  of  some  service  in  distributing  the 
fruits. 


COMMON  LIVERWORT. 
Marchantia  polymorpha  L. 


PRELIMINARY. 

THIS  plant  is  common  throughout  America  and 
Europe.  It  grows  among  grass,  over  wet  soil  or 
rocks,  in  dryer  spots  along  walls  and  fences,  and  occa- 
sionally in  more  exposed  situations,  but  is  most  luxu- 
riant in  damp  shady  places.  The  vegetative  part  con- 
sists of  flat,  green,  leaf-like  stems,  twelve  millimeters 
(half  inch)  or  so  wide  and  five  to  eight  centimeters 
(two  or  three  inches)  long,  appressed  to  the  ground, 
held  down  by  numerous  silky  hairs  on  the  under  side, 
and  much  branched,  usually  forming  extended  mats. 

There  are  two  sorts  of  reproductive  branches  which 
occur  on  separate  plants.  These  branches  (see  fig.  2) 
are  slender  stalks  about  an  inch  high,  bearing  flat  disk- 
like  heads  a  quarter  of  an  inch  or  more  across — the 
male  with  scallops,  the  female  with  finger-shaped  rays. 
The  two  forms  sometimes  grow  at  the  same  spot  or 
locality,  but  quite  as  often  entirely  apart  from  each 
other.  Besides  these  organs  there  are  often  small 
sessile  cups  (cupules)  on  the  upper  surface  of  the  stems, 
containing  green  grains. 

If  either  cupules  or  reproductive  branches  are  present, 


MARCHANTIA  POL  YMORPHA.  59 

no  other  plant  is  likely  to  be  mistaken  for  it.  In  their 
absence  it  may  be  told  from  any  of  the  lichens  by  the 
small,  diamond-shaped  markings  on  its  upper  surface. 
A  common  liverwort  growing  in  damp  places  (Conoceph- 
alns  conicus)  may  be  known  in  its  sterile  condition  by 
its  larger  size,  larger  areolae  and  more  prominent  sto- 
mata  which  in  Marchantia  are  barely  visible  to  the 
naked  eye,  but  in  Conocephalus  are  as  large  as  pinholes. 
A  common  greenhouse  liverwort  of  similar  appearance 
(Lunularia  crnciatd]  may  be  distinguished  by  its  cres- 
cent-shaped cupules,  lacking  a  border  on  one  side. 

Marchantia  grows  luxuriantly  in  the  greenhouse, 
producing  an  abundance  of  cupules,  and  often  fruit- 
ing. It  maybe  placed  on  the  pots  in  which  other  plants 
are  grown  or  given  a  bed  to  itself. 

When  gathering  material,  care  should  be  taken  to 
save  fertile  plants  with  young  heads  ;  in  female  plants, 
especially,  some  heads  should  be  no  larger  than  a  quar- 
ter the  size  of  a  pinhead,  and  which  at  this  stage  of 
growth  are  to  be  detected  in  the  sinus  at  the  growing 
end  of  the  stem. 

To  complete  the  laboratory  work  requires  fresh  or 
alcoholic  specimens  bearing  cupules  and  both  kinds  of 
reproductive  branches  ;  fresh  specimens  of  the  male  and 
female  heads  ;  and  iodine. 

LABORATORY  WORK. 
GROSS  ANATOMY. 

A.  GENERAL  CHARACTERS.     Note 
i.    The  flattened   horizontal  stem  or  thallus,  composing 
the  larger  part  of  the  plant. 


60  COMMON  LI  VER  WOR  T. 

a.  The  branches  ;  all  lying  in  the  same  plane  as  the 
main  axis,  except 

b.  The  fruiting  branches,  consisting   of  erect  stalks, 
pedicels,  supporting  disk-like  heads  or  receptacles 
of  two  sorts,  to  be  found  on  separate  plants  : 

i.     The   antheridial  (sterile)  with  scalloped  heads, 

and 
ii.  The    archegonial    (fertile)    with    star  -  shaped 

heads. 

2.  The  numerous  hairs  on  the  under  surface  of  the  thallus. 

3.  The  dark  brown  or  purple  leaves,  somewhat  concealed 
by  the  hairs,  and  closely  overlapping  to  form  a  low 
ridge  along  the  median  line  beneath. 

4.  The  scales  along   the    sides    of  the   thallus   beneath, 
some  projecting  beyond  the  margin  ;  more  conspicu- 
ous on  plants  grown  in  damp  shady  places. 

5.  Sessile  cups  or  cupules  (very  prominent  when  present), 
seated  on  the  upper  surface  of  the  thallus,  containing 
bright  green  flat  bodies,  the  gemmae. 

B.  THE  STEM.     Note 

1.  The  color  of  the  upper   and   lower   surfaces   in  fresh 
specimens. 

2.  The  well  marked  median  line,  midrib  ;  and  the  broad 
expansions,  wings,  on  either  side  of  it. 

3.  The  indented  apex. 

4.  Mode  of  branching,  dichotomous  ;  each  stem  is  resolved 
into  two  equally  diverging  stems,  one  of  which  soon 
exceeds  the  other  by  more  rapid  growth,  giving  the 
false  appearance  of  being  monopodial. 

5.  On   the    upper  surface  the   small   areas,  areolae,  best 
seen  on  the  older  parts,  in  the  center  of  each  of  which  is 


MARCIfANTIA  POLYMORPHA.  6 1 

a.  A  circular  breathing-pore,  or  stoma,  readily  de- 
tected with  the  lens.1 

6.  On  the  under  surface,  notice  the  absence  of  stomata 
and  areohi3. 

7.  Make  an  outline  sketch  of  a  branching  stem  to  show 
the  contour,  the  median  line,  and  the  mode  of  branch- 
ing. 

8.  Mount  a   transverse   section,  and  if  from  a  growing 
plant,  notice  the  pale  middle  tissue,    the    green  upper 
surface,  the  dark-colored  lower  surface,  and  the  group 
of  median  leaves  projecting  downward  from   the  mid- 
rib ;  if  from  an  alcoholic  specimen  the  color  is  wanting. 
If  the  specimen  is  very  thin  and    carefully  prepared, 
long  narrow  air-cavities  may  be  seen  just  beneath  the 
upper  surface  with  possibly  stomata  leading  out  from  the 
center  of  some. 

C.  THE  LEAF.     Remove  the  hairs  from  the  lower  sur- 
face of  the  stem,  and  notice 

1.  The  direction  and  manner  of  the  overlapping  of  the 

leaves. 

2.  The  shape. 

3.  The  curvature  and  extent  of  the  line  of  insertion. 

4.  Illustrate  shape,  and  position  on  the  stem  by  diagrams. 

D.  THE  TRICHOMES.     These  are    of    two  kinds,    the 
hairs  and  the  scales. 

i.    The  hairs.     Notice 

a.  The  silky  mass  extending  downward  along  the 
midrib,  serving  for  roots,  rhizoids  :  the  part  of  the 
thallus  from  which  they  arise. 

1  The  areolne  and  stomata  are  very  large  in  Conocephalus  conictis,  the 
latter  being  plainly  seen  without  the  aid  of  a  lens. 


6 2  COMMON  LIVER  WOR  T. 

b.      The   closely   appressed  strengthening  hairs  on  the 
wings ;   their  origin  and  direction  of  growth. 

2.    The  scales.     Notice 

a.  The  slightly  projecting  marginal  scales,  along  the 
under   edge  of  the   thallus  ;    insertion  and  direc- 
tion. 

b.  The  colorless  intermediate  scales,   midway  between 
the  edge  and  the  midrib  ;  insertion  and  direction. 

Mount  both  kinds  of  scales  and  notice 

c.  The  shape  of  each.     Draw. 

E.  THE  CUPULE.     Note 

1.  Position  on  the  stem. 

2.  Shape  and  size. 

3.  The  degree  of  smoothness  of  the   outer  and  inner  sur- 
faces. 

4.  The   thin  margin,    infolded  when  young  ;  shape  and 
regularity  of  the  teeth. 

5.  The  gemma   within  ;   remove  some   and  place  on    a 
white  surface,     and    note    their    form — usually    two 
notches  can  be  detected  opposite  each  other. 

6.  Draw  a  cupule  with  its  gemmae. 

F.  THE  FRUITING  BRANCHES. 

1.  Position  on  the   stem  ;  note  that  they  are  always  con- 
tinuations   of  the  midrib,    and   consequently    apical, 
although  sometimes,  by  the  prolongation  of  the  wings, 
appearing  to  rise  from  the  upper  surface. 

2 .  The  pedicel ;  notice 

a.      Color  and  striation. 


MARCHANTIA  POLYMORPHA.  63 

b.  The    flat,  green,  posterior*  surface  of   the    arche- 
gonial    branch,       wanting    in     the     antheridial. 

c.  Pull  a  pedicel  in  two   and  notice  the  hairs   pro- 
jecting  from   a  pair    of  grooves  on     its   anterior 
face. 

d.  Make  a  transverse  section  of   the  antheridial    ped- 
icel and    notice    the    outline,   and     the     position 
and  form  of  the  grooves.     Draw. 

e.  In   a   similar  section  of  the  archegonial    pedicel 
notice   the    outline,    grooves,    and   the  posterior 
chlorophyll-bearing  portion,  with     its    row     of    air 
cavities.     Draw. 

The  head  of  the  antheridial  branch,  consisting  of  a 
large  receptacle  and  minute  and  inconspicuous  anther- 
idia  imbedded  in  it  ;  notice 

a.  The  general  shape  of  the  receptacle. 

b.  The  particular  outline  of  the  margin. 

c.  The   broad    radiating   ridges   on  the    upper    and 

lower  surfaces. 

d.  The   narrow  wing-like  margin,   more    easily  dis- 
tinguished by  holding  the  head  toward  the  light. 

f.  The  numerous  scales  on  the   ridges   beneath,  most 
abundant  toward  the  margin. 

/.  Cut  a  vertical  section  and  observe  the  rather 
large  oval  cavities  beneath  the  ridges  ;  each  cav- 
ity contains  a  single  sac,  antheridium,  holding 
the  innumerable  fertilizing  bodies,  antherozoids,3 
neither  distinctly  visible.  If  the  antheridium  is  still 


8 1.  e.,  the  surface  looking  away  from  the  axis  of  the  stem  and  corre- 
sponding to  its  upper  surface. 

3  The  antherozoids  are  far  too  small  to  be  seen  except  with  a  compound 
microscope  ;  they  escape  through  openings  in  the  upper  surface,  also  too 
small  to  be  made  out  in  this  connection. 


64  COMMON  LI  VER  IVOR  T. 

distended  with  antherozoids,  it  will  completely 
fill  the  cavity  and  appear  as  a  darker  or  lighter 
spot  in  the  tissues,  according  to  the  thickness  of 
the  section,  but  if  the  antherozoids  have  escaped, 
the  collapsed  antheridium  remains,  although  it  can 
rarely  be  detected,  and  the  cavity  appears  empty. 
The  antherozoids  may  sometimes  be  seen  in 
mass  as  a  faint  cloud  escaping  into  the  water  of 
the  slide,  especially  when  pressure  is  applied  to 
the  cover-glass. 

g.  Make  a  horizontal  section  from  the  upper  part  of 
the  head,  after  first  removing  a  thin  surface  slice, 
and  again  observe  the  cavities. 

h.  Draw  an  uninjured  antheridial  branch,  giving 
prominence  to  the  upper  surface  of  the  head. 

4.    The  head  of  the  archegonial  branch,  consisting  of  a  star- 
shaped  receptacle  and  circle  of  reproductive  organs 
beneath  ;  notice 
a.      The  receptacle  ;  its  general  shape. 

i.    The  rays,  with  a  longitudinal  crease  beneath  ; 

their  number, 
ii.    The  cleft,  which  extends  to  the  posterior  side 

of  the  pedicel. 
/>.      The  reproductive  organs  forming  groups  alternating 

with  the  rays. 

c.      Carefully  separate  one  of  the  groups  with  a  needle, 
without  detaching  it,  and  notice 
i.    The  border,  perichsetium,  surrounding  it,   and 

inclosing 

ii.    The  several  young  sporogonia.     With  a  needle 
remove  the  sporogonia  to  a  slide  without  injur- 
ing the  perichsetium.     Now  observe  that 
iii.     The  two  halves  of  the  perichaetium  are  united 


MARCHANTIA  POLYMORPHA.  65 

at  an  acute  angle  next  the  pedicel,  and  by  an 

infolded  flap  next  the  edge  of  the  receptacle. 

This  flap  is  best  seen  by  spreading  apart  the 

rays     between     which     the     perichaetium     is 

situated, 
iv.     Remove  the  perichaetium  and  spread   out   on 

the  slide  with  the  sporogonia  already  placed 

there  ;  notice 

a.     The  fimbriated  free  edge  of  fatperichatium. 

/3.  The  opaque  sporogonia  with  their  very  short 
thick  stalks,  each  inclosed  by  a  delicate 
sheath,  the  perianth,  twice  the  length  of 
the  immature  sporogonia,  but  equaling 
or  even  shorter  than  the  older  ones. 
Draw. 

v.  Tear  away  the  perianth  and  notice  that  it  is 
quite  free  from  the  sporogonium,  which,  with 
its  stalk,  can  now  be  seen  more  clearly.  Draw. 

d.  In  a  head  from  a  fresh  specimen4  having  mature 
sporogonia  protruding  from  the  perichaetia,  notice 

i.       The /<?;•/«  of  the  sporogonia. 

ii.      The     contents ;    a    fluffy    yellow    mass    when 

escaping  from  a  freshly  ruptured  fruit, 
iii.     Mount  and  notice  the  dust-like  part,  spores, 

and  the  short  delicate  hairs,  elaters. 
iv.     Breathe  gently  upon  a  mass  of  dry  elaters  and 

notice   the   movement  caused  by   the  moisture 

of  the  breath. 

e.  Draw   an   uninjured   archegonial    branch,    giving 

prominence  to  the  under  surface  of  the  head. 

4  An  alcoholic  specimen  does  as  well,   except  to  illustrate  ii  and   iv 
infra. 


66  COMMON  LIVERWORT. 

MINUTE  ANATOMY. 

A.  THE    TRICHOMES.      Remove  some  of   the  hairs 
that  are    pressed   tightly  upon   the   under  surface  of  the 
wings  of  the  stem,  and  under  high  power  notice 

1.  The  shape. 

2.  The  internal  projections  i  sometimes  horn-like,  branched, 
and  extending  quite  across  the  cavity  of  the  hair. 

3.  The  more  or  less  prominent  spiral  constriction  on  which 
the  projections  are  seated,  giving  the  walls  in  optical 
section  the  appearance  of  alternate  scallops. 

4.  Draw. 

5.  Compare  the  loose  silky  hairs  along  the  middle  of  the 
stem,  the  true  rhizoids,  with  the  preceding.     Draw. 

Mount  marginal  and  intermediate  scales,  and  notice 

6.  The  cellular  structure  of  each.     Draw. 

B.  THE  STEM  OR  THALLUS.     Remove  a  thin  slice 
from  the  upper  surface  of  the  stem,   mount  with  the  free 
surface  uppermost,  and  under  high  power  notice 

1.  The  surface  or  epidermal  cells;  their  shape  and  con- 
tents. 

2.  The  large  breathing   pores  or  stomata,    encircled  by 
rows  of  special  cells,  the  supplementary  guard-cells ; 
number  of  cells  in  each  circle. 

3.  Draw  a  stoma  with  some  surrounding  tissue. 
Remove  the  cover-glass,   remount  the  section  with  the 

free  surface  downward,  and  disregarding  other  features, 
notice 

4.  The  four  innermost  (now  lying  uppermost)  cells  of  the 
stomata,   having  more  or  less  prominent  projections 
(sometimes  obsolete)  arching  over  toward  the  center 
of  the  pore,  the  true  or  active  guard-cells.    Draw. 


MARCHANTIA  POLYMORPHA.  67 

Take  a  very  thin  slice  in  the  same  way  from  the  lower 
surface,  and  notice 

5.  The  shape  of  the  cells  of  the  epidermis,  absence  of 
stomata,  and  the  insertion  of  the  hairs.     Draw. 

Make  a  vertical  section  of  the  stem  parallel  to  the 
direction  of  the  radiating  tissues  of  the  wings,  which  is 
usually  at  about  an  angle  of  forty-five  degrees  to  the  line 
of  the  midrib  ;  notice 

6.  The  wider  colorless  under  part  of  the  stem. 

7.  The  narrower  chlorophyll -bearing  upper  part. 
In  the  colorless  portion  of  the  stem,  notice 

8.  The  closely   packed  parenchyma  cells,   bordered   on 
one  side  by  the  marginal  row  of  cells  forming  the 
lower  epidermis. 

9.  The  shape  of  the  parenchyma  cells,  their  uniformity 
of  size,  and  the  transverse  reticulated  thickenings. 

10.  The  smaller  size  of  the  epidermal  cells,   forming  an 
indefinite  marginal  row,  the  walls  plain,   and  either 
colorless,  purple  or  brown. 

11.  Draw  several  cells  of  the  lower  epidermis,  and  some 
of  the  adjacent  parenchyma. 

In  the  upper  green  layer  of  the  stem,  notice 

12.  The  large  air  cavities,  from  the  bottom  of  which  a 
thick  growth  of  (in  fresh  specimens  very  green)  cells 
arises,  branching  in  a  cactus-like  manner. 

13.  Note  the  shape  of  these  cells,  their  manner  of  union, 
and   the    rounded   (in  fresh  specimens  bright  green) 
chlorophyll  grains.    Draw. 

In  the  same  section,  if  sufficiently  thin  and  perfect,  ex- 
amine 

14.  "^^  partition  wall  which  separates  contiguous  cavities, 


6  8  COMMON  LI  VER  WOR  T. 

and  the  over-arching  roof  formed  of  the  single  epider- 
mal layer  of  cells.     Draw. 

When  a  section  is  found  which  has  passed  through  a 
stoma,  notice 

15.  The   chimney-like   structure,    the   number   of   cells  in 
depth,  and  the  shape  of  the  cut  ends  of  the  cells,  es- 
pecially of  the  outer  and  innermost  ones.     Draw. 

16.  Illustrate  the  structure  of  the  stem  as  shown  in  the 
longitudinal  section  by  a  diagram. 

17.  Cut  a  vertical  section  of  the  wing  at  right  angles  to  the 
longitudinal  one  already  examined,  and  compare  with 
it  :  especially  note  the  difference  in  the  outline  of  the 
parenchyma  cells,  and  the  frequent  absence  of  reticu- 
lated markings.     Draw. 

C.  THE  LEAF.     Remove  a   leaf   from   the   stem,   best 
taken  from  a  young  stem  where  the  leaves  are  comparatively 
large  and  conspicuous,  and  notice 

1.  The  shape  of  the  cells,  absence  of   markings   and   of 
chlorophyll,  and  the  uniformity  of  the  cells  throughout 
the  leaf.     Draw. 

Make  a  transverse  section  of  the  stem  at  right  angles  to 
the  midrib,  and  a  good  transverse  section  of  the  leaves  will 
usually  be  obtained  :  notice 

2.  The  single  row  of  cells  forming  the  blade,  or  some- 
times two  or  three  rows  at  the  base,  and  the  manner  in 
which  the  older  leaves  over-arch  the  younger.     Draw. 

D.  THE  CUPULE.     Remove  a  cupule  and  place  face 
upward  on  the  slide,  ignoring  for  the  present  the  gemmae 
which  float  out  from  it ;  press  the  cover-glass  down  until  the 
cupule  is  sufficiently  flattened  ojit,  when  it  will  appear  as  a 
wide  ring  of  tissue,  the  bottom  of  the  cup  having  been  cut 
away.     Examine  with  low  power 


MARCHANTIA  POLYMORPHA.  69 

1.  The  border  of  triangular  teeth  ;  the  fimbriated  sides 
and  elongated  apex  of  each  tooth.     The  inner  part  of 
the  cupule  is  too  thick  to  be  seen  well. 

Place  under  a  higher  power. 

2.  Examine  the  structure  of  the/^/Aand  their  marginal  hairs 
more  carefully,  and  draw.     Vary  the  focus,  and  notice 
whether  the  inner  surface  of  the  cup  is  smooth  or  rough. 

Remove  the  cover-glass,  turn  the  specimen  over,  and  ex- 
amine as  before.  Notice  that 

3.  The  outer  surface  of  the  cup  is  covered  with  short  hairs 
vi  papilla. 

Make  a  vertical  section  passing  through  the  center  of  a 
cupule  and  through  the  stem  on  which  it  is  seated,  examine 
under  low  power,  and  note 

4.  The  two  parts  of  the  cupule. 

a.  The  base. 

b.  The  abruptly  spreading  limb. 

c.  Arising  from  the  bottom  of  the  cup,  flattened  tri- 
chomes,  the  genuine ,  in  various  stages  of  develop- 
ment. 

d.  Illustrate  with  diagram. 

Examine  the  limb  under  high  power,  noting 

5.  The  small  cells  of  the  inner  epidermis,  the  parenchy- 
matous   tissue   beneath,    the   absence   of   a   distinctly 
marked  outer  epidermis,   and  the  short  one-  or  two- 
celled  hairs  on  the  outer  surface.     Draw. 

6.  Examine  next  the  base  of  the  cupule,  noting  the  man- 
ner in  which  the  layer  of  air  cavities  of  the  stem  and 
their  chlorophyll  tissue  is  continued  up  the  outside  of 
the  cup  as  far  as  the  insertion  of  the  limb. 

7.  Upon  the  inside  of  the  cup,  observe 

a.      The  numerous   glandular,   one-celled   hairs,   and 
among  them 


7  0  COMMON  LI  VER  IVOR  T. 

b.  Thicker  hairs  in  various  stages  of  cell-multiplica- 
tion, from  the  first  division  into  two  cells  by  a 
transverse  wall,  to  the  fully  formed  many-celled 
gemma  still  attached  by  \\spedicel. 

c.  Draw  part  of  the  bottom  of  the  cup,  to  show  inser- 
tion and  form  of   the  glandular  hairs  and  young 
gemmae. 

8.    Examine  under  a  low  power  the  mature  gemmce  which 
have  floated  from  the  cupule,  and  note 

a.  The  shape. 

b.  The  cellular  structure. 

c.  Cells  here  and  there  devoid  of  chlorophyll. 

d.  The  scar  left  by  the  pedicel. 

e.  The    pair    of    vegetative    notches  placed    midway, 
one  on  the  right,  the  other  on  the  left  side,    in 
which,  when  the  gemmae  are  sufficiently  mature,  may 
be  seen 

/.      The   early  stage  of  the  new  plantlets  in  form  of 

delicate  papillae. 
g.      Draw. 
E.  THE  ANTHERIDIAL  BRANCH. 

i.    The  pedicel.     Pull  in  two  a  pedicel  and  remove  some  of 
the  hairs  which  protrude  from  two  grooves  on  its  pos- 
terior face,  and  lay  upon  a  slide.     Now  make  a  trans- 
verse section  of  the  pedicel  and  mount  with  the  hairs. 
Under  low  power,  notice 

a.  The  general  outline  of  the  section,  the  two  con- 
spicuous grooves  or  channels,  and  the  uniformity  of 
the  whole  tissue.     Illustrate  with  diagram. 

Under  high  power,  notice 

b.  The  colorless  dense  parenchyma  forming  the  mass 
of  the  pedicel,  bounded  by  the  surface  row  of  small 


MARCHANTIA  POL  YMORPHA.  1 1 

epidermal  cells,  in  fresh  specimens  usually  colored 
purple  or  brown.     Draw. 

c.  The  overlapping  projections  inclosing  the  right 
and  left  channels  or  grooves,  from  the  apex  and 
sides  of  which  arise  leaves,  which  seen  in  cross- 
section  appear  as  a  single  row  of  cells,  or  double 
rowed  at  the  base  ;  observe  the  manner  of  infold- 
ing, comparing  sections  when  convenient  from 
different  parts  of  the  same  pedicel,  and  from 
different  pedicels,  drawing  the  most  interesting. 

J.  In  some  of  the  grooves  will  be  found  excellent 
cross-sections  of  the  hairs.  Examine  now  the  hairs 
pulled  from  the  grooves.  Draw. 

e.      Remove  a  thin  paring  from  the  anterior  surface  of 

the  pedicel,  examine  the  epidermal  cells,  and,  by 

varying  the  focus,  the  face  of  the  leaves.     Draw 

a  few  cells  of  each. 

2.    The  receptacle.     Take  a  slice  from  the  ridges  on  the 

upper  surface  of  the  receptacle,   mount  with  the  free 

surface  uppermost,  and  notice 

a.      The  stomata  and  epidermal  cells. 

/>.  The  flares,  around  which  the  epidermal  cells  con- 
verge, the  mouths  to  the  underlying  cavities  con- 
taining the  antheridia. 

c.  Draw. 

Remount  the  section  with  the  free  surface  downward, 
focus  on  the  cut  surface,  and  in  the  thicker  part  of  the 
section  notice 

d.  The  large  air  cavities,  producing  from  the  sides 
branched  chlorophyll  filaments   like   those   of   the 
stem.     Focus  deeper  into  the  cavities  and  notice 
The  stomata,    the  four  innermost  cells  inflated  and 
almost  or  quite  closing  the  pore  of  the  stoma. 

/.      The  pores  of  the  antheridial   cavities  situated  in 


7  2  COMMON  LI  VER  IVOR  T. 

the  walls  between  the  air  cavities;  also  the  disposi- 
tion of  the  surrounding  tissue. 

Cut  a  rather  thick  vertical  section  a  little  to  one  side 
of  the  center  of  an  immature  receptacle,  and  notice 

g.      The  chlorophyll  cavities,with  their  chlorophyll  cells. 

h.      The  much  larger  antheridial  cavities,  which  are 

quite    likely   to   be   empty,    or   may   contain   the 

membranous  remains  of  the  antheridial  sac,  or  may 

be  more  or  less  filled  with 

3.  The  antheridium  with  its paraphyses  j  notice 

a.  The  shape  of  the  antheridium. 

b.  The  pedicel  by  which  it  is  attached  to    the  bot- 
tom of  the  cavity. 

c.  The  structure  of  the  wall,  brought  into  view  by 
focusing  on  the  part  nearest  the  eye. 

d.  The  wall  as  seen  in  optical  section,  only  a  single 
cell  in  thickness. 

e.  The    uniform   contents,   consisting   of    very   small 
squarish  cells,  filled  with  colorless  protoplasm. 

/.  The  several  unicellular  paraphyses  surrounding 
the  base  of  the  antheridium,  and  not  much  longer 
than  its  pedicel  ;  best  seen  when  the  antheridia  are 
young. 

g.  That  the  antheridia  are  younger  toward  the  margin 
of  the  head,  and  older  toward  the  center. 

h.      Draw  an  antheridium  with  its  paraphyses. 

4.  The  antherozoids  ;  if  the  section  just  examined  be  from 
a  freshly  gathered  specimen,  the  contents  of  many  of 
the  antheridial  cells  will  have  escaped  into  the  water  of 
the  slide6  ;  notice 

5  An  excellent  way  to  obtain  antherozoids  for  examination  is  to  place 
a  small  drop  of  water  on  a  slide  and  hold  a  freshly  gathered  head  in  it  for 
a  few  moments,  when,  if  the  antherozoids  are  ripe  and  abundant,  they 
will  make  the  water  milky. 


MARCHANTIA  POLYMORPHA.  73 

a.  The  rapid   motion  of  the   antherozoids,    becoming 
slower  and  slower  until  after  some  time  they  come 
quite  to  rest. 

b.  Their  form  •  a  slender  filament,  at  the  anterior  end 
of  which  may  be  detected,when  the  motion  becomes 
sufficiently  slow, 

c.  Two   very   delicate  vibratile  cilia;  the  form   and 
motion  may  be  more    readily  studied  by   staining 
with  iodine,  and  watching  the  antherozoids  as  they 
pass  gradually  under  its  influence. 

d.  The   delicate    hyaline   vesicle    and    its  contents, 
dragged     about    by    some    of    the   antherozoids 
until  finally  detached. 

If  the  section  be  from  an  alcoholic  specimen,  some  an- 
therozoids will  have  escaped,  or  can  be  made  to  escape  by 
pressing  on  the  cover-glass,  when  the  form  can  be  studied 
as  before,  but  the  filaments  will  be  found  quite  closely 
coiled,  the  cilia  difficult  to  detect,  and  the  vesicle  probably 
invisible. 

F.  THE  ARCHEGONIAL  BRANCH. 

i.    The    pedicel ;  in    a   transverse    section    under     low 
power,  notice 

a.  The  general  outline. 

b.  The  two  grooves. 

c.  The  posterior  plate   containing  air    cavities    and 
chlorophyll  tissue. 

d.  Illustrate  with  diagram. 
Under  high  power,  notice 

e.  The  larger  rounded  anterior  part,  in  every  essential 
like  that  of  the  antheridial  pedicel. 

/.      The  smaller  flattened  posterior  part  in  which  lie 
i.     The  air  cavities,  like   those   of  the  thallus,  ex- 
cept smaller,  sparsely  provided  with 


74  COMMON  LI VER  WOR  T. 

ii.     Chlorophyll-bearing  filaments ;    springing  indif- 
ferently from  the  floor  or  walls, 
iii.  The  (usually  single)   layer  of  small  cells  form- 
ing  the  floor,  partition   walls,  and  roof  of  the 
cavities. 

iv.  The   stomata,     these  will  occasionally  be  cut 
across  ;  note   the  number   of   cells  in   depth, 
and  their  relative  size. 
v.     Make  a    drawing    to    illustrate    the    several 

points. 

Make  a  longitudinal  antero-posterior  section  and  note 
g.     The  length  of  the  parenchyma  cells,  and  shape  of 

the  air  cavities. 

h.  Remove  a  thin  paring  from  the  flat  posterior 
surface  of  the  pedicel,  and  mount  with  the  free 
surface  uppermost,  noticing  the  epidermal  cells  and 
stomata.  Draw. 

i.  Remount  the  section  with  the  free  surface  down- 
ward ;  note  the  relative  size  of  the  air  cavities, 
and  the  appearance  of  the  stomata. 

Cut  off  a  pedicel  near  the  base,  make  an  antero-posterior 
longitudinal  section  of  the  basal  portion,  together  with  the 
stem  from  which  it  arises,  and  note 

j.     The  continuity  of  the  tissues  of  the  pedicel  with 

those  of  the  stem. 

Cut  off  a  pedicel  near  the  head,  make  an  antero-posterior 
longitudinal  section  passing  through  the  pedicel  and  through 
the  cleft  in  the  receptacle,  and  note 

k.     The  continuity  of  the  tissues  of  the  pedicel  with 

those  of  the  receptacle. 

2.    The  receptacle ;   cut    a  transverse  section   of  one    of 
the  rays,  and  notice 

a.  The  central  cavity  in  which  lie  numerous  hairs 
like  those  in  the  grooves  of  the  pedicel. 


MARCHANTIA  POLYMORPHA.  75 

b.     The  encircling  tissues,   indented   at  one  point,  yet 
continuous  ;  notice  further 

The  internal  portion  of  uniform  parenchyma. 
The  external  row  of  air  cavities,  containing 
chlorophyll-bearing  filaments,  and  provided 
with  stomata,  essentially  like  those  of  the 
pedicel, 
iii.  Papillary  trichomes  arising  from  many  of  the 

epidermal  cells. 

Using  an  immature  branch,  cut  a  transverse  section 
across  two  or  three  rays  nearer  the  center  of  the  head  and 
passing  through  the  groups  of  sporogonia,  notice 

c.  The  central  cavity,  much  smaller  than  in  the  rays. 

d.  The  right  and  left  sides,  which  instead  of  being 
united,  are   prolonged    into    the  perich&tium,   so 
that  the  perichaetial  leaf  on  the  right  side  of  the 
group  of  sporogonia  belongs  to  the  left  side  of 
the  right  hand   ray,  while  the  perichaetial  leaf  on 
the  left  side  belongs  to  the  right  side  of  the  left 
hand  ray. 

e.  The  section  of  the  perichaetial  leaves,    one  cell  in 
thickness,  or  sometimes  two  at  the  base. 

/.  Examine  the  flat  surface  of  the  perichaetium,  the 
shape  of  the  cells,  and  the  notched  and  fimbriated 
margin.  Draw. 

g.  The  bent  filaments,  paraphyses,  composed  either 
of  a  single  row  of  cells,  or  of  two  or  more 
united  rows  for  part  or  the  whole  length. 
Draw. 

3.    The  archegonia,6  the  flask-shaped  bodies  among  the 
paraphyses,  consisting  of 

6  Bear  in  mind  that  the  archegonia  are  called  sporogonia  after  fertiliza- 
tion and  a  certain  amount  of  growth  has  taken  place. 


76  COMMON  LIVER  IVOR  T. 

a.  The  bulbous  base  :  in  optical  section  make  out  a 
single  layer  of  cells  inclosing  a  central  cavity. 

b.  The  long  neck} 

c.  A  ring  rising  up  around  the  base  in  some  cases, 
the  early  stage  of  the  perianth. 

d.  Draw. 

4.    The   sporogonia ;  selecting  the  immature   ones,  notice 
under  a  low  power 

a.  The  perianth  ;  its  deeply  notched  margin,  which 
is  usually   twisted    over   the  fruit  ;    observe    the 
cellular  structure.     Draw. 

b.  Tear  away  the  perianth,  examine  the  surface  of 
the   sporogonium   and    its   stalk,    and    notice  the 
remains  of  the  neck  of  the  archegonium. 

c.  Crush  some  of  the  sporogonia  by  pressing  upon 
the   cover-glass,     noticing    the    escaping    contents 
consisting   of    slender  threads    having     granular 
protoplasm  and  pointed  ends,  the  immature  elaters, 
and  rows  of  young  spores,  both  radiating  from  the 
base  of  the  fruit.     Draw. 

d.  Examine  some  mature  spores  ;  notice 
i.       The  wall. 

ii.      The  contents. 

e.  Examine  the  mature  elaters  ;  notice 

i.       The  delicate  wall,  not  easily  distinguished. 

ii.      The  spiral  bands* 

iii.  Examine  some  dry  elaters  without  a  cover- 
glass,  and  observe  the  movements  when  damp- 
ened by  the  breath. 

7  These  archegonia,  unless  taken  from  a  very  young  head,  are  mostly 
sterile,  not  having  been  fertilized,  as  shown  by  the  shriveled  neck,  and 
the  absence  of  a  well  defined  protoplasmic  mass  in  the  basal  cavity. 

8  Their  number  can  be  ascertained  by  the  method  used  for  Spirogyra, 
P.  36. 


MARCHAXTIA  POLYMORPHA.  77 

Section   or  crush  a  young  archegonial  hc-.iJ.   not   exceed- 
ing a  pinhead  in  size,  and  giving  attention  only  to  the 
archegonia,  notice 
a.     The  single  layer  of  cells  forming  the  wall  of  the 

bulbous  part,  passing  into 
It.      The  few  rows  of  cells  forming  the  neck,  appearing 

in  optical  section  like  two  rows,  ending  above  in 

c.  The  stigmatic  cells,  which  are  spread  apart  at  the 
time  of  fertilization. 

d.  The  well  denned  carify  in  the  bulbous  part,  con- 
taining (if  not  yet  fertilized) 

e.  The  globular  oosphere. 

/.  The  narrow  canal  extending  the  length  of  the 
neck,  through  which  the  antherozoids  reach  the 
oosphere  to  fertilize  it. 


ANNOTATIONS. 

In  a  morphological  point  of  view  Marchantia  is  a 
plant  of  unusual  interest,  on  account  of  its  remarkable 
degree  of  differentiation.  Taking  first  the  vegetative 
portion,  we  have  in  the  thallus  a  structure  that  is 
typically  shown  in  lichens  and  other  plants  belonging 
to  the  thallophytes.  More  strictly  speaking  the  Mar- 
chantia stem  is  only  thalloid,  for  there  are  the  rudi- 
ments of  leaves  on  its  underside,  while  a  true  thallus 
has  no  leaves.  The  prostrate  position  of  the  stem  has 
necessitated  the  specialization  of  the  upper  surface  for 
the  purposes  of  assimilation  and  respiration,  and  the 
lower  surface  for  the  absorption  of  moisture  and  the 
other  nourishment  which  comes  with  it. 

The  chlorophyll  bodies,  like  those  of  all  higher  plants, 


7  8  COMMON  LI  VER  WOR  T. 

consist  of  rounded  grains  of  protoplasm  in  which  the 
chlorophyll  proper  is  contained,  the  protoplasmic  body 
being  readily  seen  after  the  pigment  has  been  extracted 
by  alcohol.  Such  grains  are  scattered  throughout  the 
thallus,  but  are  only  effectively  developed  in  special 
cells,  which  arise  from  the  floor  of  cavities  formed  by 
depressions  in  the  surface  of  the  thallus,  and  which  are 
overarched  by  the  epidermis  at  a  very  early  stage  of 
growth. 9  Communication  with  the  outside  air  is 
secured  by  means  of  peculiar  and  highly  developed 
stomata.10  They  are  wider  in  the  middle  than  at  the 
upper  and  lower  openings,  each  stoma  forming  a  small 
air-chamber.  The  border  to  the  outer  opening  is  sharp 
edged  and  immobile,  while  the  inner  one  is  formed  of 
inflated  cells  which  act  as  regulators  to  the  passage  of 
air  and  moisture.  Altogether  a  very  perfect  arrange- 
ment is  thus  made  for  the  aeration  of  the  chlorophyll 
tissue  without  undue  loss  of  moisture. 

The  under  surface  of  the  stem  is  provided  with  copi- 
ous hairs,  those  of  the  wingsdeveloped  to  give  support,11 
toward  which  the  internal  thickenings  and  spiral  con- 
striction of  the  walls  contribute,  while  those  of  the  mid- 
rib, larger,  smooth-walled,  and  somewhat  colored,  serve 
to  fix  the  plant  to  the  earth  and  to  take  up  from  it  the 
water  and  nutriment  required,  i.  e.  to  perform  the 
office  of  roots.  In  a  physiological  point  of  view 


9Leitgeb,Die  Athemoffnungen  cler  Marchantiaceen,  in  Sitzber.  d.  k.  k. 
Akad.  in  Wien,  Ixxxi,  1880.  This  differs  from  the  older  view  which 
ascribed  the  openings  to  a  separation  of  the  epidermis  from  the  under 
lying  tissues.  Sachs,  Text-book  ist  and  2nd  Eng.  eds. 

10  Described   and    illustrated  by  Voigt,    Beitrag    zur  vergleichenden 
Anatomic  der  Marchantiaceen  in  Bot.  Zeit.,  1879,  P-   729- 

11  According  to  Strasburger,  Das  botanische  Practicum,  p.  314. 


MARCHANTIA  POLYMORPHA.  79 

the  root-hairs  are  not  merely  rhizoids  but  real  roots, 
and  such  they  have  been  called  by  Sachs  recently,  who 
no  longer  holds  to  the  morphological  distinctions  of 
root,  stem,  leaf  and  hairs,  but  refers  all  vegetative 
organs  of  higher  plants  to  two  categories,  viz  :  the  root 
and  the  shoot™ 

The  scales  are  organs  that  we  shall  meet  with  in  a 
more  developed  form  when  we  reach  the  ferns.  They 
differ  from  the  leaves  in  size  and  position,  but  more 
especially  in  having  the  cells  empty  and  lifeless. 

The  internal  structure  of  the  stem  is  interesting  on 
account  of  the  thickenings  of  the  cell-walls  for  secur- 
ing extra  strength,  and  the  absence  of  any  differentia- 
tion of  the  tissues  along  the  midrib  except  the  moder- 
ate change  in  the  shape  of  the  cells. 

The  branching  of  the  stem  is  a  fine  example  of  true 
dichotomy  where  the  growing  point  is  symmetrically 
halved,  and  each  half  gives  rise  to  a  branch. 18  In  this 
case  one  branch  develops  faster  than  the  other,  and 
the  appearance  is  soon  the  same  as  if  it  had  arisen  as  a 
lateral  branch  (see  fig.  2).  The  tissues  of  the  wings 
reach  their  growth  more  rapidly  than  those  of  the 
midrib,  and  so  the  growing  end  is  constantly  indented. 

The  leaves  have  little  of  the  appearance  we  associate 
with  the  term,  as  commonly  used.  They  are,  indeed, 
very  depauperate  leaves,  and  serve  simply  as  organs 
of  strength,  through  the  power  of  the  protoplasmic 
contents  of  the  cells  to  maintain  turgidity. 

The  asexual  propagation   in   Marchantia  is  of  two 


"Vorlesungen  uber  Pflanzenphysiclogie,  p.  5. 
'•Sachs,  Text-book,  2nd  Eng.  ed.,  pp.  177,  181. 


8o  COMMON  LI VER  IVOR  T. 

kinds.  One  is  a  very  common  method,  by  which  the 
stems  die  off  at  the  older  end  as  fast  as  they  grow  at 
the  other.  In  this  way  the  branches  are  eventually 
separated  from  each  other  and  become  independent 
plants.  The  other  is  a  peculiar  method  by  which  cer- 
tain hairs  at  the  bottom  of  cupules  grow  into  flat  green 
plates,  the  gemmae,  which  as  they  become  mature  are 
pushed  out  of  the  cupules  by  the  aid  of  the  secretion 
from  the  glandular  hairs. 14  The  gemmae  have  their 
direction  of  growth  changed  at  a  very  early  stage  by 
the  formation  of  a  right  and  left  growing  point,  so  that 
the  young  plantlet  is  bifurcated  at  its  outset.  -  When 
a  gemma  has  fallen  upon  the  ground,  the  side  which 
happens  to  be  uppermost  is  developed  as  the  upper 
surface  of  the  thallus,  and  the  other  becomes  the  lower 
surface.  15  The  root-hairs  grow  from  the  cells  devoid 
of  chlorophyll. 

The  sexual  reproduction  is  among  the  most  highly 
developed  of  that  shown  by  the  liverworts.  The  organs 
are  upon  branches  whose  modification  is  so  interesting 
that  it  will  be  necessary  to  examine  it  somewhat  care- 
fully. The  plants  are  dioecious,  bearing  the  reproductive 
organs  on  separate  individuals.  In  each  case  the  repro- 
ductive branch  consists  essentially  of  an  attenuated  por- 
tion,the  pedicel,  terminated  by  an  expanded  portion, the 
head,  on  which  last  the  sexual  organs  are  borne.  The 
pedicel  is  not  a  single  branch,  but  two  which  are  the 
result  of  dichotomy  at  the  point  where  it  leaves  the 

14  Fide  Strasburger,  Das  botanische  Practicum,  p.  436. 

15  Engelmann,    Ueber  die  Einwirkung  des    Lichtes   auf   den    March- 
antienthallus  in  Arb.  d.  bot.  Inst.  in  Wurzburg,   Bd<  ii,   p.  665  ;  Mirbel, 
Mem.  Acad.  Sci.de  Fr.,  xiii  (1835),  p.  355. 


MARCH  AX  TI A  POLYMORPHA.  8 1 

thallus.  These  two  do  not  separate,  and,  indeed,  were  it 
not  for  the  two  double  rows  of  leaves  along  the  anterior 
(under)  surface,  which  give  rise  to  the  two  grooves  with 
their  strengthening  hairs,  it  would  be  difficult  to  show 
that  any  branching  had  occurred. 

The  pedicel  of  the  female  head  is  made  up  of  exten- 
sions of  the  tissues  of  the  thallus,  but  without  the 
development  of  the  wings.  The  head  is  formed  by 
sudden  branching,  and  as  dichotomous  branching  must 
always  be  in  pairs,  it  results  in  an  even  number  of 
branches  which  are  spread  out  like  a  very  widely  open 
fan.  But  counting  the  rays  of  the  head  always  gives 
an  odd  number,  which  is  explained  by  the  fact  that  the 
growing  point  is  not  at  the  tip  of  the  rays  but  at  the 
sinus  between  them,  while  the  rays  are  formed,  as  in 
the  thallus,  by  the  extension  of  tissue  on  either  side 
the  growing  point.  Thus  each  ray,  with  the  exception 
of  the  ones  nearest  the  cleft  of  the  head,  stands  between 
two  growing  points,  while  those  next  the  cleft  have  a 
growing  point  only  on  one  side  of  them.  The  hairs  of 
the  rays  correspond  with  the  hairs  of  the  wings,  and 
extend  into  the  grooves  of  the  pedicel. 

If  now  we  turn  to  the  male  branch,  we  shall 
find  the  pedicel  only  differs  from  that  of  the  female  in 
possessing  no  chlorophyll  tissue  on  its  posterior  (upper) 
surface.  The  tissues  of  the  upper  surface  of  the  head 
were  at  an  early  period  of  growth  continuous  with  those 
of  the  thallus,  but,  owing  to  some  unknown  cause,  they 
have  not  continued  to  expand  along  with  those  of  the 
ventral  side  in  forming  the  pedicel.  The  head  is  made 
up  of  branches,  as  in  the  female  head,  and  like  that  is 
not  a  radial  structure,  but  zygomorphic.  The  cleft  is 


8  2  COMMON  LI  VER  WOR  T. 

not  so  evident  as  in  the  other  case,  and  the  number  of 
rays  is  even  and  not  odd,  the  latter  being  the  result  of 
the  growing  point  being  at  the  ends  of  the  rays,  instead 
of  at  the  sinuses.  The  various  correlated  changes  can 
readily  be  worked  out  by  the  student. 

It  now  remains  to  account  for  the  position  of  the 
two  kinds  of  organs,  one  being  on  the  upper  surface 
and  the  other  on  the  lower.  We  must  know  in  the 
first  place  that  the  antheridia  are  modified  hairs,  which 
originally  started  on  the  surface,  but  became  inclosed 
in  cavities  by  the  surrounding  tissues  growing  up  about 
them.  They  evidently  belong  to  the  upper  surface 
from  their  position,  and  the  fact  that  those  nearest  the 
growing  edge  are  the  youngest.  In  the  female  inflor- 
escence we  find  that  the  organs  nearest  the  edge  are 
not  the  youngest,  but  the  oldest.  We  can  only  explain 
this  by  supposing  that  they  belong  to  the  upper  sur- 
face, but  are  brought  below  by  the  turning  under  of 
the  growing  point.16  The  perichaetium  is  the  thin  ex- 
panded edge  of  the  thallus. 

The  antheridia  and  archegonia  originate,  as  in  the 
case  of  the  gemmae,  from  papilliform  hairs,  which  divide 
into  two  cells  by  a  transverse  wall,  the  lower  cell  becom- 
ing the  pedicel,  and  the  upper  the  body  of  the  organ.17 
Paraphyses,  which  are  always  sterile  bodies,  are  very 
common  among  the  cryptogams;  their  significance  is 
not  understood. 

The  antherozoids  may  be  taken  as  the  type  of  the 
motile  male  element  in  fertilization.  They  are  formed 

16Strasburger,  Das  botanische  Practicum,  p.  439;  Leitgeb,  Unter- 
suchungen  liber  die  Lebermoose,  vi,  1881. 

17 Sachs,  Text-book,  2nd  Eng.  ed.,  p.  348. 


MARCHANTIA  POL  YMOKPHA.  83 

of  free  protoplasm,  having  no  cellulose  covering.  The 
hyaline  vesicle  which  is  sometimes  seen  attached  to 
them  arises  from  the  internal  part  of  the  protoplasm 
of  the  cell,  the  outer  portion  of  which  produces  the 
cilia,  and  the  nucleus  at  the  center  of  the  cell  the  body 
of  the  antherozoid.18 

The  archegonia  separate  a  mass  of  protoplasm  in 
their  interior,  the  oosphere,  which  is  essentially  a  naked 
cell.  After  fertilization  it  divides  in  a  perfectly  regular 
manner  to  form  the  sporogonium.  The  fertilization  is 
prepared  for  by  the  conversion  of  the  axial  row  of  cells 
of  the  neck  into  mucilage,  the  swelling  of  which  forces 
the  stigmatic  cells  apart,  and  a  passage-way  is  formed 
to  the  naked  oosphere.  The  antherozoids  pass  through 
this  channel,  become  buried  in  the  oosphere,  and  the 
fertilization  is  complete. 

The  elaters  by  their  strongly  hygroscopic  character 
assist  materially  in  forcing  out  and  distributing  the 
spores." 

18 Strasburger,  Das  botanische  Practicum,  p.  455. 

19  The  student  should  consult  Ilofmeister's  Higher  Cryptogamia,  which 
contains  a  very  full  statement  of  the  development  of  Marchantia,  with 
historical  references  up  to  1862. 


MOSS. 
Atrichum  undulatum  Beauv. 


PRELIMINARY. 

MOSSES  appear  so  much  alike  to  those  who  have  not 
given  special  attention  to  them,  that  it  is  more  difficult 
to  definitely  point  out  a  particular  species  than  in  the 
other  plants  of  the  book.  The  one  selected  for  study 
is  widely  distributed,  and  very  common,  forming  carpet- 
like  patches  in  woods,  and  on  shady  banks.  The  single 
plants  stand  from  two  and  a  half  to  four  centimeters 
(one  to  one  and  a  half  inches)  high.  The  leaves,  which 
are  abundant,  are  five  millimeters  (quarter  of  an  inch) 
or  more  long,  narrow,  with  wavy  sides  ;  the  undu- 
lations appear,  when  the  leaf  is  held  to  the  light,  as  lines 
passing  obliquely  from  the  middle  to  the  margin. 

The  male  and  female  plants  are  usually  found  in  sep- 
arate patches,  as  in  Marchantia.  The  male  flowers  (see 
fig.  5)  are  easily  recognized  by  being  cup  shape,  and  are 
distinguished  from  the  rosette  of  leaves  terminating  a 
rapidly  growing  stem  by  having  a  distinct,  rather  flat 
bottom  to  the  cup.  They  are  readily  found  at  almost 
any  time  during  the  year,  and  are  especially  abundant 
in  early  summer. 

The  female  flowers,  which  are  less  common  than  the 
male,  differ  so  little  in  external  appearance  from  the 
ordinary  vegetative  condition,  that  it  often  requires  a 


A  TR 'J 'CHUM  UNDULATUM.  85 

protracted  search  to  find  them.  A  patch  of  female 
plants  may  usually  be  detected  by  the  presence  of  the 
fruit  in  some  condition  of  growth  or  decay ;  if,  on  cut- 
ting vertically  through  astern  taken  from  such  a  group 
of  plants,  the  terminal  leaves  of  which  are  well  folded 
over  the  end,  making  a  loose  bud,  the  stem  appears  to 
terminate  abruptly  within  the  bud,  it  may  be  inferred 
that  the  female  flowers  are  found.  It  is,  however, 
necessary  to  use  the  microscope  to  render  it  sure. 
They  are  to  be  sought  for  especially  in  May.  If  the  fe- 
male flowers  can  not  be  found,  those  of  other  mosses  will 
answer  the  purpose.  Polytrichum  is  one  of  the  largest 
of  our  mosses,  and  has  female  flowers  much  like  Atri- 
chum,  while  Mnijun,  Funaria,  and  others  have  them 
somewhat  larger,  more  conspicuous,  and  nearly  as  com- 
mon as  the  male. 

The  fruit  is  a  nearly  straight  cylindrical  pod  with  a 
conspicuous  pointed  beak,  borne  erect  on  a  stalk  about 
two  or  three  centimeters  (an  inch)  long  (see  fig.  4).  Col- 
lect both  green  fruit  from  which  the  hood  (calyptra)  has 
not  fallen,  and  that  which  is  thoroughly  ripe  with  the 
hood  and  lid  both  gone,  exposing  the  teeth. 

The  protonema  is  not  so  abundantly  produced  as  in 
many  mosses.  Keeping  vigorous  growing  plants  in  an 
inverted  position  in  a  moist  atmosphere  for  some  time 
by  turning  a  bell-glass  over  them,  will  sometimes  be 
sufficient  to  develop  it.  The  protonema  from  other 
mosses  {Mnium^  Barbula,  etc.)  is,  however,  usually 
found  with  ease,  or  may  be  produced  as  above,  and  will 
serve  for  the  study. 

The  materials  required  for  the  present    study    are 


86  MOSS. 

alcoholic  specimens  showing  male  and  female  flowers, 
and  fruit ;  fresh  specimens  showing  protonema  and  male 
flowers ;  potassic  hydrate  ;  and  iodine. 

LABORATORY  WORK. 
GROSS  ANATOMY. 

A.  GENERAL  CHARACTERS.     Note 

1.  The  vertical  stem  ;  unbranched,  or  branching  only  from 
the  base. 

2.  The  leaves  clothing  the  stem. 

3.  The  root-hairs,  rhizoids ;  often  forming  a  close  felt  at 
the  base  of  the  stem. 

4.  At  the  summit  of  some  of  the  stems,  Deflowering  heads 
of  two  sorts  : 

a.  The  male  heads  forming  a  terminal  rosette  of  green 
leaves. 

b.  The  female  heads  with  the  terminal  leaves  folded 
over  each  other  forming  a  small  bud. 

5.  At  the  summit  of  other  stems  the  fruit  or  sporogoniuni, 
consisting  of 

a.  The  slender  stalk  or  seta. 

b.  The  cylindrical  pod  or  capsule. 

c.  The  hood  which  fits  closely  over  the  end   of  the 
pod,  and  may  be  easily  pulled  off,  or  has  dropped 
off  of  itself,  the  calyptra. 

6.  Among  thrifty  plants  that  have  been   kept   under   a 
moist  bell  jar  for  several  days,  notice  the  green  threads 
growing  out  over  the  soil,  the  protonema. 

B.  THE    RHIZOIDS.      Remove  some    from    the   stem, 
mount,  and  notice  the  small  tangled  hairs  forming  the  mass. 


ATRICHUM  UNDULATUM.  87 

C.  THE  STEM.     Notice  * 

1.  The  size  and  shape. 

Remove  the  leaves  near  the  base,  mount  a  transverse  sec- 
tion, and  notice 

2.  The  outline  of  the  section. 

3.  The  three  tissue  regions  ;  the   peripheral  brown  tissue, 
the  axial  tissue  forming  a  light  spot  in  the  center,  and 
the  intermediate  colorless  tissue. 

1).  THE  LEAVES.     Notice 

1.  The  manner  of  arrangement  on  the  stem. 

2.  The  difference  in  size  on  different  parts  of  the  stem. 

3.  The  shape  of 

a.  The  lowest,  scale  leaves. 

b.  The  middle,  foliage  leaves. 

c.  The  uppermost  on  flowering  stems,   forming  the 
outer  portion  of  the  head,  perichsBtial  leaves. 

4.  The  structure  ;  a  thin  lamina,  with  a  thicker  median 
line,  the  midrib. 

5.  The   character   of  the  margin,  especially  toward   the 
apex. 

6.  In  the  foliage  leaves,  the  undulations  passing  obliquely 
outward  from  the  midrib  to  the  margin  ;  their  absence 
in  the  other  sorts. 

7.  Draw  a  leaf  of  each  sort — scale,  foliage  and  perichaetial. 
E.  THE  FLOWERING  HEAD.1 

i.    The  male  heads.     Notice 

i  Called  the"  receptacle"  by  Sachs  (Text-book,  2nd  Eng.  ed.,  p. 370), 
but  this  term  has  long  been  in  use  for  the  end  of  the  stem  on  which  the 
parts  of  a  flower  are  seated.  The  analogy  of  the  several  parts  of  the 
moss  "  flower"  to  those  of  the  head  of  a  composite  (e.  g.  sunflower)  has 
determined  the  use  of  corresponding  terms. 


88  MOSS. 

a.  The  shape. 

b.  The  central  disk. 

c.  The  leafy  continuation  of  the  stem  arising  from  the 
center  of  some  of  the  heads. 

Cut  a  head  in  two  vertically,  and  note 

d.  The  enlarged  end  of  the  stem,  receptacle,  on  which 
the  disk  is  seated. 

e.  Draw  the  half  head,  looking  at  the  cut  surface. 
Remove  the  disk  with  the  point  of  a  scalpel,  separate  the 

parts  on  a  slide,  mount,  and  notice 

/.  The  broad  chaff,  resembling  the  scale  leaves  ;  the 
shape,  especially  the  narrowed  base.  Draw. 

g.  Numerous  narrow  bodies  of  nearly  the  same 
length  as  the  chaff,  antheridia,  the  male  reproduc- 
tive bodies. 

h.      Slender  filaments  of   same  length  as  the  anther- 
id  ia,  paraphyses. 
2.    The    female    heads.     Make    a    vertical    cut    exactly 

through  the  center,  and  notice 

a.  The  absence  of    any  thickening  of   the  stem  to 
form  an  enlarged  receptacle. 

b.  The  absence  of  a  disk. 

Remove   the   central   portion,   separate  well  on  a  slide, 
mount,  and  notice 

c.  The  numerous  filaments,  the  paraphyses. 

d.  A  few  bodies,  not  exceeding  a  half  dozen,3  about 
as  large  as  the  antheridia,  but  swollen  somewhat 
near  the  base  with  the  upper  portion  slender,  the 
archegonia,  the  female  reproductive  bodies. 

F.  THE  FRUIT.     Notice 

8  The  fewness  of  the  archegonia,  and  the  difficulty  of  securing  them 
at  just  the  right  stage  of  growth,  often  makes  an  extended  search  neces- 
sary in  order  to  demonstrate  them. 


ATRICHUM  UNDULATUM.  89 

1.  The  stalk  or  seta. 

a.  The  length. 

b.  Character  of  the  surface. 

c.  The   slightly  expanded  end  from  which  the  cap- 

sule arises,  apophysis. 

Take  a  specimen  that  has  been  boiled  a  minute  or  two  in 
potassic  hydrate,  and  pull  the  seta  from  the  leafy  portion, 
taking  care  that  it  does  not  break  off,  but  comes  away 
smooth,  and  notice 

d.  The  pointed  base. 

2.  The  pod  carried  by  the  seta,  the  capsule,  with  its  calyp- 
tra  ;  notice 

a.  The  manner  in  which  the  calyptra  fits  upon  the 
apex  of  the  capsule. 

b.  Shape  of  the  calyptra. 

c.  Pull  away  a  calyptra  and  note  its  texture,  and  the 
roughness  of  its  apex.     Draw. 

d.  The  shape  of  the  capsule,  and  nature  of  the  sur- 
face. 

e.  The  hemispherical   apex    bearing   a    long    beak, 
together  forming  a  removable  lid,  the  operculum. 

/.      The  obliquity  and  slightly  eccentric  position  of  the 

beak. 

£.      Draw  a  capsule. 
//.      Pull  off  the  operculum  from  a  mature  fruit,  and 

notice  the  /-/;;/  of  the  capsule  on  which  the  edge 

of  it  rested. 

/.       Rising   from   the  rim,    a  large   number   of   deli- 
cate, incurved  teeth,    together  forming  the  peri- 

stome. 
/       Count  the  teeth  ;  the  number  will  be  some  multiple 

of  four. 
/-.      The    delicate  epiphragm    stretched    between  the 

apices  of  the  teeth  ;  to  be  better  displayed  shortly. 


go  MOSS. 

I.      Draw  the  upper  part  of  the  capsule  showing  the 

teeth  and  epiphragm. 

Divide  the  capsule  longitudinally,  and  notice 
m.     The  axial  column  running  through  the  center,  the 

columella,  the  expanded  apex  giving  rise  to  the 

epiphragm. 
n.      The  cavity  between  the  columella  and  wall  of  the 

capsule,  either  empty  or  filled  with  a  powder,  the 

spores. 
o.      Make  a  diagram  of  the  section. 

MINUTE  ANATOMY. 

A.  THE  RHIZOIDS.     Under  high  power,  notice 

1.  The  straightness,  uniformity  of  diameter,  and   mode 
of  branching. 

2.  The  character  of  the  lateral  walls,  and  the  position  and 
direction  of  the  cross-partitions,  if  any. 

3.  Draw. 

4.  Notice  the  manner  in  which  some  of  the  rhizoids  are 
coiled  around  each  other,  forming  ropes. 

B.  THE  PROTONEMA.  Notice 

1.  The  arrangement  of  the  cells. 

2.  The  thinness  of  the  walls,  and  position  of  the  cross- 

partitions. 

3.  The  contents. 

4.  Draw. 

C.  THE  STEM.    In  a  transverse  section  taken  from  the 
lower  scaly  part  of  the  stem,  notice 

i.    The  three  regions. 

a.     The  peripheral,  with  the  cell  walls  reddened. 


A  TRICHUM  UND  ULA  TUM.  9 l 

b.  The  axial,  with  the  cell  walls  colorless. 

c.  The  intermediate,  with  cell  walls  yellowish. 

2.  '\\it  peripheral  tissue.     Note 

a.     The  outer   layer,   epidermis,   occasionally    bearing 

root-hairs. 
l>.     The  similar  underlying  cells,  merging  into 

3.  The  intermediate  region.     Note 

a.  The  larger  cells  with  the  walls  becoming  thinner 

toward  the  center  of  the  stem. 

b.  One  or  more  leaf  traces,  composed  of 

i.  A  crescent  shaped  layer  of  small  round  cells 
with  very  thick  walls,  the  dorsal  cells. 

ii.  Lying  in  the  crescent,  about  two  rows  of 
larger  cells  with  rather  thin  walls,  the  conduct- 
ing cells,  inclosing 

iii.  Two  or  three  small  cells,  appearing  much 
like  intercellular  spaces,  the  central  cells. 

iv.  Still  further  toward  the  center  of  the  stem,  a 
few  scattered  cells  similar  to  the  dorsal,  the 
basal  cells. 

c.  Note  that  the  leaf  traces  nearest  the  center  of  the 
stem  are  the  simplest.  Sometimes  one  may  be  found 
at  the  very  center  of  the  stem. 

4.  Draw  one  of  the  largest   leaf  traces  with  some  of  the 
surrounding  tissue  including  the  adjacent  epidermis. 

5.  Theaxia/  region.     Note 

a.     The  more  or  less  strongly  thickened  walls  of  the 
cells. 

b.  The  small  groups  of  cells  with  the  intervening  walls 
very  thin  and  membranous. 

c.  Draw  a  portion  of  the  axial  region. 

6.  In  a  longitudinal  section  of  the  stem,  identify  as   many 
of  the  different  sorts  of  cells  as  possible,  noticing 


02  MOSS. 

a.  The  shape  of  the  cells.     Draw. 

b.  The  direction  taken  by  the  leaf  traces. 

Remove   the  scales   from  a   stem,  cut  a  slice  from  the 
surface,  and  notice 

7.     The  shape  of  the  epidermal  cells.     Draw. 

D.  THE  LEAF.     Make  a  transverse  section  just  below  the 
middle  of  one  of  the  largest  foliage  leaves,  and  notice 

1.  The  larger  central  portion,  the  midrib. 

2.  The  plate  of  cells,  usually  a  single  row,  extending  right 
and  left  from  the  midrib,  the  lamina. 

3.  The  midrib.     Note. 

a.  The  epidermis  :  a  single  layer  of  cells  on  the  con- 
vex (under)  side  ;  a  layer  on  the  flat  (upper)  side, 
each  cell  of  which   gives  rise  to  a  vertical  plate, 
two  to  four   or   more  cells   in  height.     If   from  a 
fresh  specimen,  note  the  contents  of  the  cells. 

b.  The  leaf  bundle;  compare   the   several  parts,   the 
dorsal,  basal,  central  and  conducting  cells,  with  the 
corresponding  parts  of  the  leaf  trace  which  enters 
the  stem,  already  examined. 

c.  Occasionally  a  few   cells  between  the  dorsal   and 
basal  cells  and  the  adjacent  epidermis,  resembling 
the  latter. 

d.  Draw  the  midrib. 

4.  The  lamina.     Note 

a.  The  shape  and  contents  of  the  cells. 

b.  The  smaller   grouped  cells  at  the  margin  of  the 
lamina. 

c.  Draw. 

Mount  a  foliage  leaf  entire  with  the  upper  side  upper- 
most, and  beside  it  another  with  the  lower  side,  uppermost ; 
using  low  power,  notice 

9 


A  TRICH  UM  UND  ULA  TUM.  93 

d.  The  cells  of  the  main  part  of  the  lamina  with  their 
contents. 

e.  The  marginal  cells,  produced  into 

/.  The  sharp  forward-pointing  teeth,  which  are  often 
in  pairs  :  observe  the  distribution  of  the  teeth 
along  the  margin,  also  similar  teeth  on  the  under 
side  of  the  leaf  along  the  summits  of  the  undula- 
tions and  on  a  part  of  the  midrib. 

g.  The  surface  of  the  midrib :  observe  the  shape  of 
the  cells  on  the  under  side  ;  the  rows  of  chlorophyll 
tissue  on  the  upper  side,  which  begin  near  the  base 
of  the  leaf  and  extend  nearly  to  the  apex,  seen  as 
plates  in  the  transverse  section. 
Under  high  power,  notice 

//.  The  elongated  marginal  cells,  and  the  shorter  cells 
forming  the  teeth. 

/.  Draw  a  portion  from  near  the  middle  of  the  leaf, 
showing  teeth,  marginal  cells  and  some  adjacent 
laminal  cells. 

E.  THE  FLOWERING  HEAD.     Remove  the  disk  from 
a  male  head,  and  mount,  well  separated  ;  notice 

1.  Numerous  hairs,  \hzparaphyses. 

a.  The  walls,  cross  partitions,  and  contents. 

b.  Draw. 

2.  The  antheridium. 

a.  The  shape. 

b.  The  elongated  cells  of  the  body. 

c.  The  short  cells  of  the  pedicel. 

d.  The  large  apical  cell,  in  antheridia  which  have  not 
yet  burst. 

e.  Draw. 

3.  The  antherozoids.     If  from  a  fresh  specimen,  notice 


94  MOSS. 

a.  The  movement.     Apply  iodine,  and  watch  them  as 
they  gradually  come  under  its  influence. 

b.  The  form  ;  a  slender  body,  with  a  pair  of  cilia  at 
the  anterior  end. 

c.  The  colorless  vesicle  sometimes  to  be  seen  attached 
to  the  posterior  part. 

d.  Draw. 

Crush  an  immature  antheridium  by  pressing  on  the  cover- 
glass,  and  as  the  contents  escape,  notice 

e.  The  antherozoids  coiled  within  the  mother-cell. 

If  alcoholic  specimens  are  used,  the  antherozoids  may  be 
seen  within  the  mother-cell,  but  the  parts  can  not  be  made 
out. 

Tear  apart  a  female  head,  mount,  and  notice 

4.  The  paraphyses  j  shape  and  structure. 

5.  The  archegonia. 

a.  The  enlarged  ventral  portion. 

b.  The  long  neck. 

c.  The  short  thick  pedicel. 

d.  Focus  upon  the  surface,  and  draw  some  cells  of 
each  portion. 

Treat  with  potassic  hydrate  to  render  the  archegonia 
more  transparent,  focus  so  as  to  give  an  optical  section,  and 
notice 

e.  The  two  rows  of  cells  forming  the  neck,   the  ter- 
minal cells  of  which  are 

f.  The  stigmatic  cells. 

g.  The  canal  along  the  axis  of  the  neck. 

h.      The  two  or  more  rows  of  cells  surrounding  the 

ventral  portion. 
i.       The  small  mass  of  protoplasm  lying  deep  in  the 

center  of  the  ventral  portion,  the  oosphere  (if  not 

yet  fertilized). 


ATRICHUM  UNDULATi'M.  95 

J.       Draw. 
F.  THE  FRUIT. 

1.  The    seta.     In   a   transverse  section   near    the    base, 

notice 
a.      The  outer  portion  of  thick  walled,  deeply  colored 

tissue,  passing  abruptly  into 
/'.       Loose,  thin  walled,  colorless  tissue.     Within  these 

and  almost  completely  separated  from  them 

c.  A  core  composed  of  the  following  tissues  : 

i.     An  outer  row  of  large,  round,  thin  walled  cells, 
ii.    Adjoining  this  a  layer  of  smaller  angular  cells 

with  walls  somewhat  thickened,  and 
iii.  In   the     center,  a  few   small   cells  with  thin 

colorless  walls. 

d.  Draw  a  sector  of  the  section. 

e.  Notice  the  shape  of  the  epidermal   cells  in  a  sur- 
face slice.    Draw. 

/.      Examine  several  longitudinal  sections,  and  deter- 
mine as  many  of  the  tissues  as  possible.     Draw. 

2.  The  capsule.     Make  a  transverse  section  through  the 
middle  of  an    immature  capsule.     Under  low  power, 
notice 

a.  Two  parts,  separated  by  a  cavity  : 

i.      The  outer,  the  wall  of  the  capsule. 
ii.     The  inner,  the  axial  cylinder. 
iii.    Uniting   these,  if  not  torn  away  in  making 
the  section,  delicate  radial  filaments. 

b.  The  parts  of  the  axial  cylinder. 

i.     The  narrow  outer   part,    the  wall  of  the  spore 

case. 

ii.     The  large  central  part,  the  columella. 
iii.     A  dark  line  separating  the  two,  the  mother- 
cells  containing  the  young  spores. 


96  MOSS. 

c.  Make  a  diagram  of  the  section. 
Under  high  power,  examine  in  succession 

d.  Each  of  the  tissues  enumerated. 

e.  Draw  a  sector  of  the  section. 

Make  a  transverse  section  of  a  mature  capsule,  notice 
/.      The  thick  walled,  deep  colored  and  strongly  cuti- 

cularized  epidermis. 
g.      The  colored  cells  of  the  spore  sac. 
Make  a  longitudinal  section  of  a  nearly  mature  capsule 
(after  removing  the  calyptra),  and  with  low  power,  notice 
at  the  base  of  the  capsule 

h.      A  mass  of  large  thin  walled    cells    forming   the 

apophysis. 

i.       Above   the   apophysis   several    layers    of  smaller, 
more  regular  cells,  from  which   arise  the  various 
parts  of  the  axial  cylinder. 
j.      At  the  upper  end  of  the  capsule,  notice 

i.  The  large  central  mass  of  wide  thin  walled 
cells,  resting  upon  the  axial  cylinder  and 
inclosed  by  the  operculum. . 

ii.  The  line  of  separation  between  this  and  the 
roof  of  the  operculum,  showing,  more  or  less 
clearly,  the  delicate  membrane  which  is  ex- 
posed by  the  detachment  of  the  operculum, 
the  epiphragm. 
iii.  The  small  deeply  colored  cells  of  the  rim  of 

the  capsule. 

iv.  The  curved  lines  extending  from  the  rim 
to  the  edge  of  the  epiphragm,  the  structure 
usually  not  well  shown,  the  teeth  of  the  peri- 
stome. 

v.  The  tissue  of  the  operculum  on  the  sides 
where  "it  shuts  over  the  teeth,  of  the  roof 
adjoining  the  epiphragm,  and  of  the  beak. 


A  TRICHUM  UND  ULA  TUM.  97 

/-.      Illustrate  the  arrangement  of  the  tissues  as  seen 

in  longitudinal  section  by  a  diagram. 
Take  a  nearly  mature  capsule,  remove  the  thinnest  pos- 
sible slice  from  the  side  of  the  operculum  with  the  razor 
inclined  toward  the  beak  ;  the  next  slice  will  include  a  por- 
tion of  the  peristome,  in  which  notice 

/.       The   rows    of  cells    from    which   the   teeth   are 
formed,  and  their  manner  of  thickening.     Draw. 
Make  several   transverse  sections  through  the  rim  and 
operculum,  and  study 

m.     The  formation  of  the  teeth  from  groups  of  cells. 
Take  a  mature  capsule,  mount  a  number  of  entire  teeth, 
and  notice 

//.      The  shape  and  structure  of  the  teeth.     Draw. 
o.      Flatten  out   a  calyptra,  and  observe  the  cellular 
structure,  especially  at    the    apex.     Draw    some 
of  the  cells. 

3.    The  mature  spores  ;  note  under  high  power 
a.      The  shape. 
A      The  wall  and  contents. 

ANNOTATIONS. 

The  step  from  Marchantia  to  Atrichum  is  not  so 
great  as  that  which  intervenes  between  the  several 
preceding  examples,  and  yet  the  advancement  is  well 
marked  and  especially  significant.  With  the  upright 
growth  of  Atrichum  is  correlated  the  disposition  of  the 
leaves  and  root-hairs.  The  leaves  being  green,  relieves 
the  stem  of  its  assimilative  duties,  and  in  consequence 
the  smaller  size  and  greater  firmness  better  meet  the 
requirements.  The  root-hairs  simulate  true  roots  even 


98  MOSS. 

more  closely  than  those  of  Marchantia.  A  curious 
habit  of  the  root-hairs  of  this  and  the  allied  genera  is 
the  manner  in  which  they  coil  about  each  other,  form- 
ing branching  ropes,  and  adding  to  their  effectiveness 
as  hold-fasts. 

The  stem  of  Atrichum  shows  considerable  diversity 
of  tissues.  The  axial  groups  of  cells  with  thin  inter- 
mediate walls  are  peculiar  to  a  few  of  the  higher 
mosses.  A  noticeable  feature  is  the  absence  of  a  well 
marked  epidermis,  which  is  doubtless  to  be  associated 
with  the  fact  that  the  cells  beneath  have  thick  walls,  that 
there  are  no  chlorophyll  tissues  to  be  aerated,  and  that 
the  numerous  leaves  assist  materially  in  giving  protec- 
tion. The  absence  of  stomata  is  also  to  be  accounted 
for  by  the  absence  of  chlorophyll  tissues. 

The  leaves  show  a  distinct  midrib  and  blade,  and 
possess  all  the  essential  features  of  true  foliage  leaves. 
The  blade  being  only  one  cell  thick  is  apparently  the 
same  on  both  sides,  and  possesses  chlorophyll  bodies 
which  are  typical  for  all  higher  plants.  A  selvage  of 
strong  cells  runs  around  the  edge  of  the  lamina  to 
guard  against  tearing,  while  numerous  teeth  act,  to 
some  extent,  as  a  protection.  To  give  additional  aerat- 
ing surface,  there  are  a  number  of  plates,  like  narrow 
auxiliary  blades,  placed  along  the  upper  surface  of  the 
midrib.  They  are  still  better  developed  in  Polytri- 
chnmy  but  are  entirely  wanting  in  most  mosses.  As 
there  is  no  epidermis  or  other  protective  structure  to 
guard  against  excessive  evaporation,  an  ingenious  sub- 
stitute is  afforded  by  the  inrolling  of  the  sides  of  the 
leaf  whenever  the  turgidity  of  the  cells  is  disturbed. 

But  no  feature  in  the  histology  of  mosses  is  more 


A  TRICHUM  UXDULA  TL  MA  99 

significant  and  interesting  than  the  leaf  bundle  of  the 
midrib.  It  is  the  simplest  form  of  a  structure  that 
plays  a  most  important  part  in  higher  plants — the 
framework  of  wood  and  bark  which  enables  them  to  rise 
above  the  surface  of  the  earth  and  display  their  tissues 
to  the  wind  and  sun  under  conditions  most  favor- 
able for  growth.  The  bundles  of  Atrichum  which  are 
as  highly  developed  as  in  any  of  the  mosses,  resemble 
those  of  higher  plants  more  in  their  position  and 
function  than  in  structure.8  Their  place  in  the  leaf 
and  their  manner  of  forming  leaf-traces  in  the  stem  are 
like  those  of  higher  plants.  The  cells  for  strength  are 
the  dorsal  and  ventral,  being  the  same  except  in  posi- 
tion, and  the  cells  inclosed  by  these  transport  the  sap. 

Passing  to  the  sexual  reproduction,  we  notice  that 
the  organs  concerned  are  much  like  those  of  Marchantia. 
The  differences  requiring  consideration  lie  in  the  modes 
of  displaying  and  protecting  the  organs.  Instead  of 
sinking  the  male  organs  in  a  flattened  receptacle,  they 
are  placed  in  the  axils  of  protecting  leaves  diverted  to 
that  use,  and  instead  of  bringing  the  female  organs 
under  the  protecting  roof  of  the  receptacle  they  are 
sheltered  from  rain  and  other  excessive  moisture  by 
the  overlapping  of  the  perichaetial  leaves. 

An  item  of  historical  interest  in  this  connection  is 
that  it  was  in  the  mosses  that  the  sexual  organs  of 
cryptogams  were  first  demonstrated  by  Hedwig4  in 
1783,  but  it  was  not  till  the  publication  of  Suminski's 
researches  on  the  ferns,5  as  late  as  1848,  that  their 

3  A  very  full  illustrated  account  of  the  histology  of  the  stem  and  leaves 
of  mosses  is  given  in  Pringsheim's  Jahrb.  f.  wis.  Bot.,  vi. 

4  Theoria  Generationis,  p.  138. 

5  Zur  Entw.  der  Farrnkrauter. 


100  MOSS. 

sexual  character  was  fully  established.  It  was  also  in 
mosses  and  liverworts  that  the  antherozoids  were  first 
detected,  being  seen  by  SchmideP  in  1762,  but  without 
detecting  their  cilia,  which  were  discovered  by  Unger7 
in  1837. 

After  fertilization  has  occurred  the  oosphere  clothes 
itself  with  a  cell  wall,  and  grows  at  once  into  a  fruit,  as 
in  Marchantia.  This  fruit  is  in  many  ways  remarkable, 
as  will  be  more  apparent  in  some  respects  after  study- 
ing the  ferns  and  club-mosses.  It  will  be  remembered 
that  in  the  plants  already  studied,  with  the  exception 
of  Marchantia,  the  sexually  formed  spore  produced  a 
plant  like  the  parent,  after  a  longer  or  shorter  period  of 
rest.  In  Atrichum,  however,  it  grows,  not  into  a  plant 
like  the  parent,  but  into  a  highly  complicated  structure, 
the  fruit  or  sporogonium,  which  in  its  turn  forms 
asexual  spores  that  produce  plants  like  the  original. 
This  process,  known  as  an  alternation  of  generations,8 
is  less  strongly  marked  in  liverworts,  and  reaches 
its  height  in  ferns. 

The  base  of  the  seta  which  is  thrust  into  the  apex  of 
the  leafy  plant,  has  no  organic  connection  with  it,  and 
while  in  Atrichum  it  pulls  out  with  some  difficulty,  in 
many  mosses  it  comes  away  easily  without  preparatory 
treatment.  This  feature  further  emphasizes  the  dis- 
tinctness of  the  so-called  fruit  and  the  parent  plant, 
from  which  in  quite  a  parasitic  fashion  it  derives  its 
nourishment. 


6  Icones  plantaram,  p.  85. 

7  Nova  Acta  A.  C.  L.-C.  Nat.  Cur.,  xviii,  p.  791. 

8  Sachs,  Text-book,  2nd    Eng.  ed. ,   pp.    226,954;  Vines,    Journal   of 
Botany,  1879  ;  Underwood,  Our  native  ferns  and  their  allies,  p.  35. 


ATRICHUM  UNDULATUM.  lot 

The  tissues  of  the  seta  attain  rather  higher  devel- 
opment than  those  of  the  stem.  The  cortical  part  is 
provided  with  a  well  formed  epidermis,  while  the  axial 
part  is  composed  of  several  tissues,  the  two  portions 
being  separated  by  thin-walled  parenchyma.  At  the 
apophysis,  where  the  seta  expands  at  its  upper  end, 
many  mosses  produce  stomata  quite  like  those  of 
higher  plants.  In  rarer  instances  they  occur  on  the 
capsule  or  seta.  Their  presence  or  absence  seems  to 
signify  nothing  as  to  relationship,  as  there  is  no  more 
constancy  in  their  occurrence  among  the  highest  than 
among  the  lowest  forms." 

The  capsule  of  Atrichum  does  not  differ  widely  from 
that  of  other  mosses,  except  in  the  teeth  and  epi- 
phragm,  and  otherwise  requires  no  particular  explana- 
tion. The  teeth  are  composed  of  groups  of  cells 
arranged  as  a  series  of  U's  placed  side  by  side.  In  all 
other  mosses  except  the  immediate  allies,  where  teeth 
are  present  at  all,  they  are  formed  of  the  thickened 
sides  of  the  cells,  and  not  of  whole  cells.10  The  epi- 
phragm,  which  joins  the  apices  of  the  teeth  like  a  thirf 
membrane,  is  formed  without  thickening  or  special 
preparation  of  the  walls.  The  spores  escape  by  being 
shaken  from  the  capsule  through  the  openings  between 
the  teeth,  as  from  a  pepper  box. 

The  calyptra,  which  is  the  result  of  the  aftergrowth 
of  the  archegonium,  was  early  torn  away  from  its 
attachment  at  the  base  of  the  fruit  and  carried  up  by 
the  elongating  seta  as  a  hood  for  the  capsule. 


9  Valentine,  Trans.  Linn.  Soc. ,  xviii,  p.  239. 

10  Sachs,  Text-book,  2nd  Eng  ed.,  p.  383. 


102  MOSS. 

The  spores  germinate  by  producing  a  protonema, 
which  may  grow  to  considerable  length,  with  numerous 
branches,  before  a  leafy  stem  is  formed.  The  successive 
inclinations  of  the  transverse  walls  of  the  protonema 
have  been  shown  to  follow  the  same  laws  as  govern  the 
successive  divisions  of  the  apical  cell  to  form  the  leafy 
stems,  so  that  we  are  to  consider  the  protonema  as  an 
excessively  attenuated  stem,  from  which  the  leafy  stems 
arise  as  lateral  branches. 


THE  MAIDEN-HAIR  FERN. 

A dia n t u ui  pe da tuin  L . 

PRELIMINARY. 

THE  maiden-hair  fern  is  abundant  in  dark  rich  woods 
throughout  the  eastern  part  of  the  United  States,  and 
occurs  to  a  considerable  extent  west  of  the  Rocky 
Mountains.  It  may  be  recognized  with  certainty  by  the 
forking  of  the  polished  purple  leaf-stalk  into  two  equal 
recurved  branches,  which  give  rise  to  a  number  of 
straight  branches  upon  one  side,  bearing  the  oblong 
leaflets.  On  the  back  of  the  leaflets,  along  their  mar- 
gins, are  born  the  crescent-shaped  fruit  dots. 

Underground  stems  and  roots  (together  popularly 
called  roots),  and  leaves,  including  the  leaf-stalks,  should 
be  collected  when  the  fruit  dots  assume  a  yellowish 
brown  hue,  which  is  usually  about  the  middle  or  latter 
part  of  August.  The  roots  should  be  taken  up  with 
care  and  the  dirt  shaken  from  them  gently  to  avoid 
tearing  off  the  root-hairs  and  root  tips,  and  the  clean- 
ing completed  with  water.  Part  of  the  leaves  and  all 
of  the  stems  and  roots  should  be  preserved  in  alcohol, 
the  remainder  of  the  leaves  by  drying  between  news- 
papers or  in  a  plant  press. 

The  prothallia  of  Adiantum  are  less  known  popu- 
larly. They  are  flat,  roundish,  green  bodies,  two 
to  five  millimeters  (l/lt  to  l/B  inch)  in  diameter, 


104  MAIDEN-HAIR  FERN. 

deeply  notched  on  one  edge,  and  held  to  the 
ground  by  a  cluster  of  root-hairs  from  the  under 
side.  They  may  be  found  on  the  surface  of 
damp  ground  near  patches  of  the  fern,  and  may  be 
collected  and  preserved  in  alcohol.  If  a  green-house 
is  accessible,  prothallia  may  usually  be  obtained 
fresh  and  in  quantity  from  the  surface  of  pots  and 
earth  near  which  native  or  exotic  species  of  Adiantum 
are  growing.  If  neither  source  yields  suitable  material, 
the  prothallia  may  be  grown  by  sowing  the  spores  of 
Adiantum  (to  be  obtained  from  the  fruit  dots  on  the 
margins  of  the  leaflets)  on  the  surface  of  damp  earth 
packed  smooth  and  kept  at  first  under  a  bell-glass  in  a 
good  light.1  Strasburger3  recommends  sowing  the 
spores  on  the  surface  of  a  piece  of  pressed  peat  (pre- 
viously boiled  in  water  to  destroy  other  spores)  which 
is  to  be  kept  saturated  with  a  nutritive  solution  pre- 
pared according  to  the  formula  given  on  page  34.  The 
peat  should  be  covered  by  a  bell-glass  and  placed  near 
a  north  window.  If  prothallia  of  Adiantum  can  not  be 
obtained,  the  prothallia  of  almost  any  fern  will  show 
the  characteristic  features  of  this  stage. 

It  will  be  advisable  before  attempting  to  cut  sections 
of  the  rhizome  to  soak  it  for  a  few  minutes  in  water  in 
order  to  soften  the  tissues  somewhat,  for  when  taken 
from  alcohol  they  are  extremely  hard.  Care  will  have 
to  be  exercised  in  cutting  these  sections  not  to  nick  the 
edge  of  the  razor  ;  it  will  need  frequent  sharpening. 
Before  cutting  the  sections,  the  end  from  which  they 
are  to  be  cut  should  be  smoothed  with  a  knife. 

1  Cf.  Campbell,  Bot.  Gazette,  x,  p.  356. 

2  Das  botanische  Practicum,  p.  457. 


ADI  A  NTUM  FED  A  TUM.  1 05 

The  requisites  for  the  complete  study  of  this  plant 
are  dried  and  alcoholic  specimens  of  leaves  ;  alcoholic 
specimens  of  roots  and  stems  ;  fresh  prothallia  ;  alco- 
hol ;  iodine  ;  potassic  hydrate  ;  and  solution  of  potassic 
chlorate. 

LABORATORY  WORK. 
GROSS  ANATOMY. 

A.  GENERAL    CHARACTERS.      Taking    a    complete 
plant,  notice  the   four  parts  into  which  it  may  be  readily 
divided  : 

1.  The  horizontal,  very  dark  brown,  or  almost  black,  un- 
der-ground stem,  the  rhizome,  from  which  are  given  off 

2.  A  number  of  slender  branching  fibers,  the  roots. 

3.  The  aerial  portion,  the  leaf  or   frond,    consisting   of 
slender  polished  stalks,  and  flat  green  expansions,  the 

blades. 

4.  The  appendages  to  the  surface,  trichomes,  in  the  form 
of  scales  on  the  rhizome,  hairs  on  the  roots,  and  repro- 
ductive bodies  on  the  leaves. 

B.  THE  STEM  or  RHIZOME.     Notice 

1.  The  size,  shape  and  surface. 

2.  The  occasional  branching. 

3.  The  nodes  and  internodes ;  the  nodes  are  indicated  by 
the  growth  of  a  leaf  at  each,  alternately  on  the  right 
and  left  sides  ;  the  intervals  between  the  nodes  are  the 
internodes. 

4.  The  growing  apex  ;  the  dying  base. 

5.  The  buds   near   and  at  the  apex.     Strip  off  carefully 


io6  MAIDEN-HAIR  FERN. 

from  several  buds  the  numerous  brown  scales  which 
clothe  them.     Note  the  two  kinds  : 

a.  Buds  showing  a  rudimentary  leaf  whose    stalk  is 
coiled  upon  itself,  thus  :    ^ 

b.  One  or  more  buds  whose  central  part  is  simply  a 
continuation  of  the  stem. 

6.  Make  an  outline  drawing  of  the  rhizome,  showing  the 
size,  shape,  mode  of  branching  and   arrangement  of 
leaves  and  buds. 

7.  The  structure.     Cut  across  the  rhizome  at  right  angles 
to  its  length  and  examine  the  cut  surface.     Observe 

a.  The  outer  ring  of  brown  tissue,  the  cortical  layer. 

b.  The  oval,    circular,  or  C  -shaped  white  mass,  the 
fibro-vascular    bundle.     Where   a   branch    or   leaf 
arises  two  fibro-vascular  bundles  will  be  seen,  thus  : 
C  ^-     Find  a  part  of  the  rhizome  showing  such  an 
arrangement,  and  trace  the  course  of  the  bundles 
(by  cutting  a  series  of  rather  thick  sections)  through 
at  least  two  internodes,  noting  the  modes  in  which 
successive  branches  are  given  off  from  the  bundle. 
The  smaller   C  -shaped   portion  passes   into    the 
nearest  leaf  ;  the  other  gradually  enlarges,  closes 
into  a  circle,  elongates  into  an  oval,  becomes  egg- 
shape,  and  finally  opens  to  form  two  unequal  C  's« 
the  smaller  of  which  soon  enters  the  second  leaf  on 
the  opposite  side  of  the  rhizome  from  the  first. 

c.  Inclosed   by  the  fibro-vascular  bundle   a   darker 
brown  mass  not  differing  otherwise  from  that  sur- 
rounding the  bundle. 

d.  Make  an  enlarged  drawing  of  the  cut  end  of  the 
stem. 

Cut  a  rhizome  longitudinally  through  the  center,  and  on 
the  cut  surface  make  out 


ADIANTUM  PEDA  TUM.  1  o  7 

e.  The  parts  previously  seen  in  the  transverse  sec- 
tion. Draw. 

/.  The  scales.  Mount  a  few  scales  from  the  rhizome, 
and  note 

i.     Their  shape  and  texture. 
ii.     Their  structure  j  the  shape  and  arrangement  of 

the  cells, 
iii.     Draw  a  scale  enlarged. 

C.  THE  ROOTS.     Notice 

1 .  The  shape. 

2.  The  mode  of  branching. 

3.  Their /#.«//<?//  on  the  rhizome. 

4.  The  covering  of  tangled  root-hairs  with  which  some  are 
enveloped. 

5.  The  absence  of  root-hairs  near  the  w\i\\\s\\  growing  end. 

6.  The  brownish  tip  (sometimes  torn  off),  the  root-cap. 

7.  Examine  a  tranverse  section  of  a  root,   and  compare 
with  that  of  the  stem.     Note  the  position  of  the  fibro- 
vascular  bundle.     Draw  the  section. 

D.  THE  LEAF.     It  may  be  easily  distinguished  into  two 
parts,  the  stalk,  rhachis,  with  its  branches,  and  the  green 
blades,  pinnules. 

i.    The  main  rhachis  and  its  branches.     Note 

a.  The  polished  surface. 

b.  The  shape  ;    a  little  flattened  on  the  anterior  sur- 
face (i.e.,  the  one  corresponding  to  the  upper  sur- 
face of  the  leaf).      Dried  or  alcoholic  specimens 
are  likely  to  have  this  surface  flat  or  concave  while 
the  posterior  remains  convex.      Note  the  slight 


MAIDEN-HAIR  FERN. 

ridges  between  these  two  surfaces,  more  marked 
in  dried  or  alcoholic  than  in  fresh  specimens. 
The  color  of  the  anterior  and  posterior  surfaces. 
The  branching.  At  the  top  the  rhachis  divides 
into  two  equal  (or  almost  equal)  divergent 
branches.  Each  of  these  again  divides  into  two, 
one  of  which  forms  the  rhachis  of  a  pinna  (to  be 
described  shortly),  while  the  other  again  forks. 
Note  the  number  of  times  such  forking  occurs  and 
the  relative  length  of  the  secondary  rhachises  thus 
formed.  Make  a  diagram  showing  the  above 
points. 

e.  The  structure.     Cut  transverse  sections  of  the  stalk 
at  various  heights.     Make  out  the  same  structure 
as  detailed  for  the  rhizome.     Notice 

i.     That  the  brown  tissue  of  the  stem  is  largely 

replaced  by  a  whitish  one,  parenchyma. 
ii.     The  different  shape  of  the  sections  of  the 

fibro-vascular    bundle    at      various     heights 

along  the  stalk, 
iii.     Trace  its  course  near    the    forking   of    the 

stalk  until  it  divides,  one-half  entering  each 

branch, 
iv.     Make  diagrams  showing  these  points. 

f.  Compare  the  scales  on  the  base  of  the  leaf-stalk 
with  those  studied  from  the  rhizome. 

The  pinna.  Each  pinna  is  composed  of  a  slender  pol- 
ished rhachis  bearing  a  number  of  leaflets,  the  pinnules. 
Note  the  variation  in  the  number  of  pinnules  on  a 
rhachis  and  the  general  outline  of  a  pinna.  Make  an 
outline  drawing  of  a  pinna. 

Theflinnutes.  Selecting  a  pinnule  near  the  middle  of 
the  rhachis,  observe 


PEDATUM.  109 

a.  The  shape  as  to  outline  and  margin. 

b.  Draw  carefully  an  outline  of  the  pinnule  studied. 

c.  Compare  the  shape  of  the  terminal   pinnule  with 
those  near  the  middle  of  the  rhachis.     Note  that 
it  is  like  two  of  the  latter  joined  by  their  bases. 
Compare  also  the  basal  pinnules  with  the  middle 
ones.     Draw  an  outline  of  the  terminal  and  basal 
pinnules. 

d.  The  surface,  texture,  and  color. 

e.  The  structure.     Notice 

i.  The  slender  stalk  at  the  angle  formed  by 
the  lower  and  basal  edges,  attaching  the  pin- 
nule to  the  rhachis. 

ii.  The  slender  branching  threads,  veins,  ex- 
tending  from  the  apex  of  this  stalk  and 
supporting 

iii.     The  green  substance  of  the  pinnule,  the  mes- 
ophyll,  which  fills  all  the  space  between  the 
veins. 
/.      The  arrangement  of  the  veins,  venation.     Notice 

i.     One  vein  a  little  stronger  than  the  rest,  par- 
allel with  and  close  to  the  lower  edge. 
The  mode  of  branching. 
That   the   veinlets   are   not  connected  into  a 
network. 

iv.  Compare  with  the  venation  of  the  basal  and 
terminal  pinnules. 

v.  In  the  outline  drawings  of  the  terminal,  basal 
and  middle  pinnules  already  made  draw  the 
veins. 

4.    The  reproductive  bodies.     Observe 

a.      On  the  upper  edges  of  the  under  side  of  the  pin- 
nules a  large  number  of   crescent  shaped  spots, 


1 1 o  MAIDEN-HAIR  FERN. 

sori.     Note  the  pinnules  from  which  they  are  most 
uniformly  absent. 

Soak  a  pinnule  in  water  for  a  few  minutes  and  with  the 
needles  turn  back 

b.  The  flap  which  covers  a  sorus,  the  indusium.  Notice 
that  it  is   a   portion   of  the  edge  of  the  pinnule 
reflexed  and  peculiarly  modified. 

c.  On  the  under  side  of  the  indusium,  a  mass  of  yel- 
lowish spheroidal  bodies,  the  sporangia. 

Scrape  away   most  of  the  sporangia  from  the  surface,  and 
notice 

d.  The  relation  of  the  points  of  attachment  of  the 
sporangia  to  the  veins.     Cut  off  and  draw  an  indu- 
sium showing  this. 

5.    The  sporangia.     Mount  some  of  the  separated  sporan- 
gia and  examine  by  oblique  light.     Note 

a.  Their  shape. 

b.  The  short  stalk  by  which  they  were  attached. 

c.  The  ridge,  slightly  darker  than  the  rest,  extending 
part  way  round  the  sporangium,  the  annulus. 

d.  Burst  a  sporangium  and  note  the  contents,  minute 
powdery  bodies,  the  spores. 

c.  Study  the  manner  of  bursting  and  scattering  the 
spores.  Tear  a  bit  of  an  indusium  from  a  dried 
specimen  previously  soaked  in  water,  retaining 
only  a  few  sporangia  ;  place  it  on  a  slip  of  glass 
and  allow  it  to  dry,  while  watching  the  sporangia 
through  a  lens,  illuminating  them  from  above.  A 
crack  appears  on  the  side  where  the  annulus  is 
absent,  which  gapes  more  and  more  as  the  annulus 
straightens  and  becomes  recurved.  After  bending 
backward  a  certain  distance,  by  a  sudden  jerk 
whereby  the  spores  are  scattered,  the  annulus 


ADIANTUM  FED  A  7  I '.]/.  1 1 1 

becomes  straight  again  (or  almost  so),  and  very 
gradually  resumes  the  same  position  as  before  the 
rupture  of  the  sporangium. 

E.    THE    PROTHALLIUM.       Examine     prothallia   of 
various  ages.     Notice 

1.  The  shape  and  size. 

2.  The   cellular  structure,  best  seen   in  a  mounted  speci- 
men. 

3.  The  cluster  of  rhizoids  on  the  under  side. 

4.  That  in  a  prothallium  with  a  young  fern  plant  attached 
the  plant  arises  from  the  under  surface. 

5.  Draw. 
MINUTE  ANATOMY. 

A.  THE  STEM.     Cut  a  transverse  section  and  examine 
with  a  low  power.     Make  out  the  following  parts  : 

1.  The  single  outer  row  of  cells,  the  epidermis. 

2.  A  considerable  thickness  of  brown1  thick-walled  tissue, 
the  peripheral  sclerenchyma. 

3.  A  circular,  oval   or  Q  -shaped  mass  of  whitish  tissue, 
most  of  which  is  \fatfibro-vascnlar  bundle. 

4.  Surrounding  this   bundle,  and   marking  its   outline,  a 
chain-like  row  of  minute  oval  cells,  the  bundle-sheath. 

5.  Entirely  or  partially   surrounded  by  the  fibro-vascular 
bundle,  a  mass  of  axial  sclerenchyma  similar  to  the  peri- 
pheral. 

Examine   the  section   with    a  high  power  and  study  in 


Yellowish  in  very  thin  sections. 


*l*  MAIDEN-HAIR  FERN. 

detail  each  of  the  tissues  and  groups  of  tissues  seen  above, 
in  the  following  order  : 

6.  The  epidermis.     Observe 

a.  That  the  outer  wall  is    thicker  than  the  lateral  and 
inner   ones.      In   favorable  sections  a   very   thin 
layer,  the  cuticle,  may  be  seen  covering  the  outer 
wall. 

b.  That  the  epidermal  cells  contain  numerous  round- 
ish or  somewhat  angular  starch  granules?     Treat  a 
freshly-cut   section   with  iodine,    and   notice   the 
color  produced. 

i.       Study  one  of  the  starch  grains.     Notice  the 
central  lighter  spot,  the  nucleus.6 

c.  Draw  several  epidermal  cells. 

7.  The  sclerenchyma,  peripheral  and  axial.     Note 

a.  How  greatly  the  walls  are  thickened. 

b.  That  adjoining  walls  consist  of  three  or  more  dis- 
tinct layers,  the  thin  central  one  of  which  is  the 
middle  lamella. 

c.  The  perforations  or  pits,  which  extend  through  the 
thickening  layers  to  the   middle  lamella  at  right 
angles  to  the  surface  of  the  wall.     Observe  that 
the   pits  in  contiguous  cell  walls  correspond   to 
one  another. 

d.  Examine  the  middle  lamella  at  a  point  where  three 
or  four  cells  meet.     Note  that  it  divides,  inclosing 
a  triangular  or  quadrangular  space  which  is  filled 

4  The  occurrence  of  starch  in  epidermal  cells  is  unusual. 

6  The  term  as  here  used  has  an  entirely  different  signification  from 
that  which  it  has  as  applied  to  a  cell.  Here  it  denotes  a  central  watery 
spot,  about  which  lie  the  layers  of  the  starch  grain,  alternately  more  and 
less  watery. 


ADI  A  Ar  T  UM  PEDA  TUM.  1 1 3 

with  a  thickening  deposit,  similar  to  that  of  the 

inner  layers  of  the  wall. 
e.      The  abundance  of  starch  in  this  tissue. 
/.      Draw  several  sclerenchyma  cells  showing  these 

points. 

8.  The  cortical  parenchyma^  lying  just  outside  the  bundle- 
sheath  in  some  places.     Observe 

a.  That  the  walls  are  thin  and  colorless,  with  trian- 
gular intercellular  spaces  ;    contents  of  the  cells, 
granular  protoplasm  and  starch. 

b.  Compare    carefully   the    middle    lamella   of    the 
sclerenchyma  with  the  walls  of  the  parenchyma 
where  the  two  tissues  merge. 

c.  Draw  several  parenchyma  cells. 

9.  The  bundle-sheath.     Notice  the  emptiness8  of  the  cells, 
their  shape,  and  the  position  of  their  longer  axes. 

10.  The  fibro-vascular  bundle;  easily  distinguishable  into 
two  regions  :  first,  a  central  one,  the  xylem,  char- 
acterized by  the  numerous  large  openings  of  the 
scalariibrm  vessels,  with  small  cells,  the  xylem  paren- 
chyma, packed  between  them  ;  secondly,  a  peripheral 
one,  the  phloem,  showing  cells  of  much  more  uniform 
diameter,  and  lying  between  the  xylem  and  the  bundle- 
sheath.  This  region  contains  phloem  parenchyma  and 
sieve  cells,  Study  carefully  each  of  the  above 
named  tissues.  Commencing  at  the  bundle-sheath, 
examine 

a.  The  phloem  parenchyma  ;  composed  of  two  or  three 
(occasionally  but  one)  irregular  rows  of  small  thin- 
walled  cells  next  the  bundle-sheath  and  a  few  cells 

6  Sometimes  a  few  starch  grains  appear  to  lie  in  them  ;  they  have  been 
pulled  over  by  the  razor  in  cutting. 


H4  MAW£tf-HAlR  FERN". 

here  and  there  between  the  sieve  cells  (to  be 
pointed  out  directly),  all  filled  with  granular  pro- 
toplasm and  small  starch  grains.  Compare  with 
cortical  parenchyma. 

b.  The  sieve  cells  ;    lying  between  the  main  body  of 
phloem  parenchyma  and   the  scalariform  vessels. 
Note  their  angular  shape,  slightly  thickened  walls 
and  emptiness,  except  for  a  little  granular  material 
clinging  to  the  walls. 

c.  The  scalariform  vessels.     Observe 

i.  That  wherever  two  vessels  are  in  contact  their 
contiguous  walls  are  flattened,  and  the  vessels 
are  therefore  irregularly  polygonal,  having 
two  or  three  sides  much  longer  than  the 
others. 

ii.  That  they  are  thicker  at  the  angles  than  on 
the  sides,  and  thus  appear  to  be  united  only 
at  the  angles. 

iii.  The  narrow  slit  between  the  contiguous  sides 
of  the  vessels. 

iv.     The  emptiness  of  the  vessels. 

d.  The  xylem  parenchyma;  small  cells  packed  between 
the  scalariform  vessels,  and  similar  ones  near  their 
periphery.     Note  their  contents. 

e.  Notice    the  general   arrangement   of   the  tissues, 
making  it  a  concentric  bundle. 

/.  Draw  sufficient  of  the  fibro-vascular  bundle  and 
its  sheath  to  show  the  different  tissues  and  their 
relations  to  one  another. 

Cut  a  longitudinal  radial  section  of  the  stem  in  the  plane 
of  the  leaf  stalks.  Examine  with  a  low  power,  and  make 
out 

ii.    The  epidermis. 


ADIANTUM  PEDA  TUM.  1 1$ 

12.  The  sclerenchyma,  peripheral  and  axial. 

13.  The  double  band  of  whitish  tissue,  consisting  of  cortical 
parenchyma,  bundle-sheath  and  fibro-vascular  bundle. 

Examine  the  section  with  a  high  power,  studying  each 
tissue  seen  in  the  transverse  section. 

14.  The   epidermis ;    compare  the  length  of  its  cells  with 
the  same  in  transverse  section.     Draw  a  few  cells. 

15.  The  sclerenchyma  ;  cells  elongated  with  tapering  ends. 
Note  the  pits  and  the  middle  lamella  as  in  transverse 
section.     The  mouths  of  the   pits  may  be  seen  when  a 
wall  extends  across  a  cell.     Draw. 

1 6.  The    cortical  parenchyma;    as   in    transverse   section 
except  that  the  cells  are  elongated. 

17.  The    bundle-sheath  ;  the  length  and  narrowness  of  the 
cells. 

18.  The   fibro-vascular    bundle ;    the    two    regions  distin- 
guished   in    transverse   section,    xylem    and  phloem. 
Commencing  at  the  bundle-sheath  notice 

a.  The  phloem  parenchyma  ;  much  as  in  the  former 
section. 

b.  The   sieve  cells ;   their  great  elongation,  tapering 
ends  overlapping    succeeding   ones,  and  slightly 
thickened    walls.     Note    the   sieve  plates  on  the 
side  walls,  looking  like  irregular  thin  spots  with 
fine  specks  in  them;  or  the  sections  of  them  on  the 
cut  edges  of  the  vessels,  as  depressions  of  the  sur- 
face of  the  wall,   paired,  one  on  each  side  when 
two  sieve  vessels  are  contiguous.7 

c.  The  scalariform  vessels.     Observe 

7  Under  a  £  or  ^  objective  the  pores  in  the  sieve  plates  may  be  bet- 
ter seen.     Consult  Bessey,  Botany,  fig.  71,  p.  81. 


1 16  MAIDEN-HAIR  FERN. 

i.  That  the  walls  of  these  vessels  present  many 
narrow  thin  spaces,  looking  like  slits  placed 
transversely. 

ii.       That  these  thin  spaces  do  not  extend  entire- 
ly across  the  face  of  a  vessel. 

iii.  Find  a  place  where  the  contiguous  walls  of 
two  vessels  have  been  cut  through  by  the 
razor  and  observe  the  beaded  appearance  of 
the  walls.  Each  "bead  "  corresponds  to  the 
thick  part  of  the  wall  and  the  intervals  to  the 
thin  places. 

Isolate  some  scalariform  vessels  by  boiling  a  rather  thick 
longitudinal  section  for  a  few  seconds  in  potassic  chlorate 
solution.  Mount  in  water  and  examine  with  a  high  power  8 

iv.     The  shape  and  markings.     Draw. 
d.      Draw  the  fibro-vascular  bundle  with   a  portion  of 
the  bundle-sheath. 

19.    The  trichomes,  in  the  form  of  scales.     Mount  scales  of 
various  shapes  under  the  same  cover,  and  observe 

a.  The  shapes  and  arrangement  of  the  cells,  espec- 
ially at  the  apices  of  the  scales. 

b.  Draw  a  scale.      .   . 

B.  THE  ROOT.     Cut  a  transverse  section  of  one  of  the 
larger  roots,  examine  with  a  high  power,  and  note 

1.  At  the  edge  of  the  section  (if  perfect)  the  epidermis?  of 
irregular  thick-walled  cells,  not  differing  much  from 

2.  The    underlying    brown  parenchyma,   which  gradually 
merges  into 

8  If  the  vessels  do  not  separate  in  mounting,  press  gently  on  the  cover- 
glass  with  a  little  sidewise  push. 

9  So  called  here  because  of  its  position  ;  not   necessarily  homologous 
with  the  epidermis  of  the  stem. 


ADI  A  N  TUM  FED  A  7  Y  J/.  I  I  7 

3.  Yellowish  sclercncJiyma,  similar  to  that  of  the  rhizome. 
Notice  the  starch,   increasing  in  quantity  toward  the 
center. 

4.  Draw  a  portion  of  the  above  tissues. 

5.  Note  the  abruptness  with  which  the  sclerenchyma  joins 

6.  The  fibro-vascular    bundle.     Notice    the    sheath  which 
encircles  it.10 

a.  Just  within  the  bundle-sheath,  a  row  of  parenchy- 
ma cells  with  granular  contents  (protoplasm)  ei.cir- 
cling  the  bundle,  the  pericambium. 

b.  The  xylem  region  •  consisting  of 

i.  Scalariform  vessels ;  four  (sometimes  three  or 
five)  of  which,  occupying  the  center  of  the 
bundle,  are  in  pairs,  one  pair  larger  than  the 
other  ;  the  remainder,  much  smaller,  are  in 
t\vo  clusters,  one  between  the  vessels  of  the 
smaller  pair  and  the  pericambium  on  each 
side.  If  the  scalariform  vessels  are  not  easily 
made  out,  a  section  may  be  treated  with  pot- 
ash or  stained  with  iodine.  They  then  become 
very  plain. 

ii.      Xylem  parenchyma;  packed  between  and  imme- 
diately around  the  larger  vessels. 

c.  The  phloem   region ;  its    two   parts   separated  by 
the  xylem,  lie  outside  of  the  vessels  of  the  larger 
pair  and  consist  of  parenchyma  with  granular  con- 
tents and  empty  sieve  vessels. 

7.  Considering  the  whole  bundle,  notice  that  all  the  tis- 
sues it  contains  are  symmetrically  disposed  about  a  cen- 
ter.    It  is  therefore  known  as  a  radial  bundle. 

10  The  bundle  sheath  frequently  breaks  in  cutting. 


n8  MAIDEN-HAIR  PERM. 

8.  Draw  the  bundle. 

Take  one  of  the  largest  roots  whose  root-cap  is  present 
and  cut  a  series  of  longitudinal  sections,  mount,  treat  with 
potash,  and  selecting  the  section  which  passes  through  the 
center  of  growth,  note 

9.  The  concentric  layers  of   the  root-cap,  each  thickest  in 
the  middle,  the  outer  sloughing  off. 

10.  The  tissues  at  the  apex  of  the  root.     In  the  center,  im- 
mediately under  the  root-cap,  a  large  triangular  cell, 
apex  inward,  the   apical  cell.       Notice  that  the   cells 
adjacent  to  the  inner  faces  of  the  apical  cell  have  evi- 
dently been  derived  from  it  by  partitions  parallel  to  its 
faces. 

11.  Draw  the  tip  of  the  root,  including  the  root-cap. 

12.  The  trichomes  in  the  form  of  root-hairs.     Slice  off  from 
a  root  a  thin  piece  carrying  a  number  of  hairs,  and 
note 

a.  Their  attachment  to  epidermal  cells. 

b.  The  shape  of  a  hair  near  the  proximal  and  distal 
ends. 

c.  The  color  of  the  wall  and  absence  of  septa. 

d.  The  occasional  spiral  thickenings  in  the  large  hairs, 
usually  forming  a  loose  spiral  of   three  or  four 
turns  only. 

<?.       The  contents. 

f.      Draw  a  hair  showing  these  points. 

C.  THE  LEAVES. 

i.  The  epidermis.  Lift  the  epidermis  of  the  lower  surface 
of  a  leaflet  with  the  point  of  a  needle,  seize  it  with  fine 
forceps  and  strip  off  as  much  as  possible,  mount, 
examine  with  high  power,  and  notice 


ADIAXTUM  PEDATUM.  HQ 

a.  The  very  irregular  shape  of  the  cells  and  the  way 
in  which  they  dovetail  into  each  other. 

b.  Here    and    there    narrow   slit-like   stomata,  each 
bounded  by  two  crescentic  cells,  the  guard  cells. 

c.  Along  certain  lines  (over  the  veins)  the  different 
shape  of  the  cells. 

J.  The  chlorophyll  bodies,  especially  in  the  guard  cells  ; 
their  granular  nature. 

e.      Make  a  drawing  showing  these  points. 

/.  Examine  in  the  same  way  the  epidermis  of  the 
upper  surface  of  a  leaflet ;  note  the  absence  of 
stomata. 

Cut  a  vertical  section  of  a  leaflet  at   right  angles  to  the 
veins.     Observe 

g.  On  each  side  of  the  section  the  irregular  epider- 
mis, containing  chlorophyll  bodies.  On  a  draw- 
ing of  the  surface  view  of  the  epidermis  draw 
imaginary  lines  in  various  directions  and  note 
the  differing  lengths  of  the  lines  across  any  cell. 
This  will  explain  the  different  lengths  of  the  epi- 
dermal cells  cut  by  the  razor. 

//.  Occasionally  a  stoma  in  the  epidermis,  bounded 
by  the  two  guard  cells,  communicating  with  an 
intercellular  space  ;  note  the  shape  of  the  guard 
cells. 

2.  Occupying  the  space  between  the  upper  and  lower  epi- 
dermis, the  loosely  arranged  irregular  parenchyma  of 

*  the  leaf,  mesophyll,  also  containing  chlorophyll. 

3.  The  large  intercellular  spaces  of  the  parenchyma. 

4.  At  intervals  along  the  section  the  cut  ends  of  the  reins. 
Identify  the  tissues  with  those  seen  in  the  stem. 

5.  Beneath  the  vein,  forming  a  part  of  the  lower  surface 


120  MAIDEN-HAIR  FERN. 

of  the  leaf,  will  be  seen  three  or  four  very  thick-walled 
cells. 

6.  Draw  the  vertical  section  of  the  leaf. 

Bend  a  leaflet  over  the  finger  and  cut  the  thinnest  possi- 
ble slice  from  the  under  surface  lengthwise  of  the  veins. 
Mount  with  the  cut  surface  upward,  and  note 

7.  The  length  of  the  cells  over  the  veins  and  the  manner 
of  overlapping,  fibrous  tissue,     Draw. 

8.  The  trichomes  in  the  form  of  sporangia.     Scrape  some 
sporangia  from  a  sorus  of  a  dried   specimen,   examine 
dry  with  a  low  power,  and  note 

a.  The  shape  and  color. 

b.  The  row  of  brownish  walled  cells  extending  part 
way  around  the  sporangium,  the  annulus. 

c.  The   stalk  by  which  they  were  attached. 
Examine  with  a  high  power  sporangia  from   alcoholic 

specimens,  mounted  in  water  with  cover,  and  note 

d.  The  structure  of  the  wall  of  the  sporangium.    This 
can  be  best  studied  in  some  of  the  immature  spor- 
angia which  can  usually  be  found  in  the  same  sorus 
with  the  mature.     Supplement  this  study  by  exam- 
ining the  wall  of  a  bursted  sporangium.     Observe 
that  the  wall  consists  of  a  single  layer  of  much 
flattened  cells.     Note  the  nuclei. 

e.  The  annulus.     Study  the  cells  which  compose   it. 
Notice  that  it  forms  a  distinct  ridge  and  is  cpn- 
tinued  beyond  the  point  where  the  cells  are  thick- 
est by  a  series  of  short  broad   cells  with  thinner 
walls. 

/.  The  stalk  ;  the  number  of  cell  rows  which  com- 
pose it  and  the  absence  of  any  trace  of  a  fibro- 
vascular  bundle. 


ADI  ANT  UM  PEDATUM.  12 1 

g.      Draw  a  sporangium. 

//.  The  place  of  attachment.  Scrape  away  most  of 
the  sporangia  from  an  indusium,  mount  it,  and 
notice  the  place  of  attachment  of  the  remaining 
sporangia  and  of  the  bases  of  the  stalks  of  the 
others.  Observe  its  relation  to  the  vein. 

/.  The  mode  of  dehiscence.  Tear  off  a  bit  of  indu- 
sium bearing  a  few  sporangia,  from  a  dried  speci- 
men previously  soaked  in  water,  place  on  a  slip 
without  a  cover  glass  and  allow  it  to  dry  while 
examining  it  with  a  low  power,  illuminating  it 
from  above.  Watch  the  process  of  bursting  care- 
fully. 

j.  The  spores.  In  unbursted  sporangia  from  alco- 
holic specimens  notice  how  closely  they  are 
packed.  Examine  some  which  have  escaped, 
and  note 

Their  shape  and  contents. 
Their  double  walls.  Burst  some  spores  by 
pressing  on  the  cover.  In  favorable  speci- 
mens the  outer  layer  of  the  wall,  exospore, 
will  be  ruptured  and  the  delicate  inner  layer, 
endospore,  with  its  inclosed  protoplasm  will 
be  seen  protruding. 

D.  THE  PROTHALLIUM.  Carefully  brush  away  all  the 
dirt  from  the  under  side  of  a  prothallium  of  medium  size 
and  mount  it  with  the  under  side  uppermost.  Examine 
with  a  low  power,  and  notice 

1.  The  shape  and  the  character  of  the  margin. 

2.  The  shapes   of  the  cells.     Draw    a  few  cells  of    the 
prothallium  showing  the  various  shapes. 

3.  The  abundant  chlorophyll  bodies. 


122  MAIDEN-HAIR  FERN. 

4.  The  absence  of  fibro-vascular  bundles. 

5.  The    trichomes    in   the   form     of     hairs    of     various 
kinds. 

a.  Shorter   or  longer  pointed  hairs  on  the  surface 
and  margin." 

b.  Short  blunt  hairs  in  like  positions. 

c.  Rhizoids.     Note 

i.     Their  various  sizes  and  lengths, 
ii.     The  irregular  shape.     Draw. 

6.  Roundish     bodies     of    considerable    size    near    and 
among  the  rhizoids,  the  sexual  organs. 

Examine  with  a  high  power,  and  notice  the  two  sorts  : 

a.      Some  bodies    spherical    and   filled   with   smaller 
cells,  the  antheridia.     Observe 

i.     The   single  layer  of  cells   forming   a   wall la 

which  incloses 

ii.  A  cluster  of  spherical  cells,  the  sperm  cells.  13 
iii.  If  fresh  material  is  being  used,  some  mature 
antheridia  will  probably  have  been  ruptured 
in  mounting  and  the  sperm  cells  with  their 
antherozoids  have  escaped.  Note  the  movements 
of  the  antherozoids  after  they  have  escaped 
from  the  sperm  cells.  Kill  them  by  treating 
with  iodine,  watching  them  as  they  come 
under  its  influence.  Take  note  of  the  body  of 
the  antherozoid,  a  spirally  coiled  filament  to 
which  is  usually  attached  an  almost  empty 

11  Sometimes  wanting. 

12  Best  seen  in  immature  antheridia.     All  stages  may  usually  be  found 
on  the  same  prothallium. 

13  If  the  structure  of  the  antheridia  can  not  be   made   out  easily  here, 
postpone  the  study  till  D,  8.  a.  is  reached. 


ADIAXTTM  PEDATUM.  123 

vesicle,  and  of  the  numerous  cilia  l4  at  the  free 
end  of  the  body.     Draw. 

iv.     If    no    fresh   prothallia   are   procurable   the 

antherozoid   may  be  seen  within  the  sperm 

cell  in  alcoholic  specimens,  but  its  parts  are 

not  distinguishable. 

v.      Draw   both    young   and   mature   antheridia, 

showing  structure  and  contents. 

/>.  Some  bodies,  of  similar  shape  to  antheridia  but 
apparently  composed  of  four  cells  either  quadrant- 
shaped  and  meeting  in  the  middle  or  somewhat 
oval  leaving  a  squarish  space  between  them,  the 
archegomd, 

\.       In    favorable  fresh  specimens  one   or  more 
moving    antherozoids    may    be  seen   in   the 
space,  canal,  between  the  four  cells. 
Cut  several  vertical  sections  of  the  prothallium,  passing 
through  the  region  of  the  notch  and  the  cluster  of  rhizoids. 
Treat  with  potash,  examine  with  a  high  power,  and  notice 

7.  The    number  of   cells   in    thickness  of  various    parts 
of  the  prothallium  ;  especially  its  rapid  thickening  in 
the  region  of  the  rhizoids. 

8.  The  sexual  organs.1* 

a.      The     globular      antJieridia,     wholly     superficial. 

Notice  the  thickness  of  the  wall  in  mature    and 

immature  ones. 
/'.      The  archegonia  may  be  recognized  by  the  more 

or  less  recurved    projecting   neck    composed   of 

several  rows  of  cells.     Note 

14  Difficult  to  see.     Use  ^th  or  higher  objective  if  possible. 

15  If  their  structure  has  not  been  comprehended  before,  it  may  be  easily 
made  out  now  by  examining  numerous  sections  of  the  prothallium. 


1 24  MAIDEN-HAIR,  FERN. 

i.     The  number  of  rows  of  cells  composing  the 
neck. 

ii.  The  canal  between  the  cells  of  the  neck,  and 
extending  from  its  apex  to  the  imbedded 
portion  of  the  archegonium.  This  canal  is 
difficult  to  distinguish  unless  it  contains  a 
granular  substance. 

iii.  The  cluster  of  cells  at  the  base  of  the  neck 
imbedded  in  the  prothallium,  the  body  of  the 
archegonium. 

iv.  At  the  inner  end  (base)  of  the  canal,  in  the 
midst  of  the  cells  of  the  body,  a  single  large 
central  cell,  filled  with  a  rounded  mass  of  pro- 
toplasm, the  oosphere. 

v.      Draw  the  archegonium. 

ANNOTATIONS. 

Regarding  only  the  position  of  organs,  perhaps  the 
most  striking  difference  between  Adiantum  and  Atri- 
chum  is  to  be  found  in  the  fact  that  the  former  has  its 
leaves  only  above  the  ground,  while  the  real  stem  is 
buried  below  it.  In  contrast  with  those  low  plants 
whose  rhizoids  have  served  them  well  enough  for  hold- 
fasts, the  fern  has  developed  strong  fibrous  roots  which 
ramify  widely  and  perform  this  office,  assisted  by  the 
buried  stem.  These  roots  are  made  necessary  not 
only  by  its  greater  stature  and  the  consequently  greater 
strains,  but  by  the  necessity  of  wider  foraging  for  the 
supply  of  food.  The  roots  must  push  their  way 
among  the  particles  of  soil,  and,  to  protect  the  tender 
tissues  of  the  growing  point,  the  tip  of  the  root  is 
covered  by  a  cap  of  cells,  which  arise  from  segments 
cut  off  from  the  outer  face  of  the  tetrahedral  apical  cell. 


ADIAXTTM  Fl-DATl'M.  125 

As  the  cap  is  gradually  disorganized  and  worn  away  by 
contact  with  the  soil  it  is  replaced  by  new  growth  from 
behind.  The  root  cap  is  to  be  considered  as  a  modified 
and  augmented  portion  of  the  epidermis.16 

Provision  for  continued  growth  of  the  stem  in 
length  is  found  in  the  bud  at  its  apex.  The  dying 
base,  however,  follows  with  equal  pace  the  advancing 
apex,  severing  the  lateral  branches  as  it  reaches  them, 
which  thus  become  independent  plants. 

One  of  the  most  marked  advances  upon  the  structure 
of  the  moss  is  to  be  found  in  "the  development  of  an 
extensive  and  complicated  fibro-vascular  system.  The 
simple  leaf  traces  of  Atrichum  are  here  replaced  by 
better  developed  groups  of  fibers  and  vessels  to  which 
the  term  fibro-vascular  bundle  is  applied.  These 
bundles  are  distributed  to  every  part  of  the  plant ;  con- 
densed in  those  parts  requiring  strength,  such  as  the 
roots,  stem  and  leafstalk  ;  diffusely  branched  in  the 
leaflets  for  the  support  of  the  chlorophyll-bearing 
tissue.  Branches  of  the  fibro-vascular  bundles  having 
once  been  formed,  do  not  reunite  with  their  fellows, 
either  as  a  whole  or  by  anastomosing  branchlets.  The 
only  organs  of  Adiantum  not  reached  by  the  fibro- 
vascular  bundles  are  the  numerous  and  unusually 
varied  trichomes.  These  are  developed  as  scales 
thickly  clothing  the  stem  and  base  of  the  leaf  stalk,  as 
hairs  matted  together  about  the  roots,  and  as  sporan- 
gia crowded  under  the  edges  of  the  leaflets. 

In  the  growing  parts  of  all  organs  of  the  fern,  the 
cells  are  parenchymatous,  but  certain  groups  early  dif- 

16  Bessey,  Botany,  p.  163. 


126  MAIDEN-HAIR  FERN. 

ferentiate  into  the  tissues  which  compose  and  surround 
the  fibro-vascular  bundles.  These  tissues  are  quite  dis- 
tinct from  each  other  as  well  as  from  the  original 
parenchyma. 

The  sheath  which  incloses  the  bundles  does  not 
belong  to  the  bundle  itself,  either  in  the  fern  or  other 
plants,  but  to  the  surrounding  parenchyma. 

The  apparently  perforated  plates  on  the  walls  of  the 
sieve  cells  can  not  be  seen  clearly  because  of  the  layer 
of  protoplasmoid  substance  which  adheres  to  the  walls. 
The  perforations  themselves  are  not  easily  demon- 
strated though  DeBary  "  thinks  he  has  seen  fine  fila- 
ments connecting  granules  on  opposite  sides  of  a  plate. 
The  continuity  of  protoplasm  between  other  than 
sieve-cells  has  been  demonstrated  in  many  plants. 

The  arrangement  of  the  tissues  of  the  bundles  in 
stems  and  roots  is  of  different  types.  In  the  former, 
the  phloem  of  the  bundle  encircles  the  xylem  whence 
it  is  known  as  a  concentric  bundle.  In  the  latter, 
the  xylem  forms  a  plate  dividing  the  phloem  into 
two  portions' which  stand  one  on  each  side  of  it. 
Assuming  a  center,  the  xylem  and  phloem  masses  are 
symmetrically  disposed  about  it,  whence  the  bundle  is 
known  as  radial.18 

The  root-bundle  contains  a  tissue,  the  pericambium, 
whose  cells  are  still  capable  of  division  ;  no  such 
tissue  is  found  in  the  stem-bundles.  New  roots  have 
their  origin  not  in  the  pericambium  as  in  phanerogams, 
but  from  cells  of  the  bundle-sheath.19 

17  Comparative  Anatomy,  p.  181. 

18  Cf.   Strasburger,  Das  botanische  Practicum,  p.  209  ;  DeBary,  Com- 
parative Anatomy,  p.  362. 

19  Cf.  Strasburger,    Das  botanische    Practicum,  p.   276  ;     Prantl  and 
Vines,  Text-book  of  Botany,  p.  51. 


ADIAXTL\M  PEDATL'M.  127 

The  original  parenchyma  outside  the  bundles  of  the 
stem  early  thickens  its  walls.  These  thick  walls  con- 
sist of  several  layers,  the  most  prominent  of  which,  the 
median,  is  called  the  middle  lamella.  This  layer, 
according  to  Strasburger30  and  others,  is  the  primary 
cell  wall,  upon  which  thickening  layers  are  deposited. 
By  other  histologists  it  is  held  that  the  layers  are 
formed,  as  the  thickening  progresses,  by  the  differenti- 
ation of  the  wall.  Growth  in  thickness,  according  to 
the  first  view,  is  due  to  apposition  ;  according  to  the 
second,  to  intussusception. 

The  thickening  layers  of  the  wall  are  perforated  by 
numerous  pits,  through  which  probably  pass  threads  of 
protoplasm,  not  occupying  the  breadth  of  the  pit,  but 
passing  through  much  more  minute  openings  in  the 
closing  membrane  of  the  middle  lamella." 

In  addition  to  serving  to  increase  the  strength  of 
the  stem,  the  cortical  part  is  a  convenient  storehouse 
for  reserves  of  food,  as  indicated  by  the  quantity  of 
starch  in  its  cells. 

The  several  cell  layers  of  the  leaf  necessitate  some 
arrangement  for  allowing  the  entrance  of  gaseous  food 
and  exit  of  the  by-products  of  the  cells'  activity ; 
hence  the  loose  arrangement  of  the  cells  of  the  leaf, 
forming'  large  intercellular  spaces,  which  communicate 
with  the  exterior  by  numerous  stomata.  The  stomata 
have  here  the  form  usual  among  the  higher  pteri- 
dophytes  and  flowering  plants,  an  elliptical  slit,  bounded 
by  two  crescentic  cells,  which  by  their  change  of  posi- 

90  Bauund  Wachsthum  der  Zellhaute,   p.  175. 

Sl  Cf.  Schaarschmidt,  Protoplasm,  Nature,  xxxi,  p.  290 ;  Gardiner, 
ibid,  p.  390. 


128  MAIDEN-HAIR  FERN. 

tion  may  either  open  more  widely  or  almost  close  the 
orifice. 

The  prothallium,  which  is  developed  from  a  spore 
produced  by  the  leaf,  bears  little  resemblance  to  the 
mature  spore-bearing  fern  plant.  In  its  flattened  shape, 
cellular  structure  and  rhizoids  it  does,  however,  have  a 
striking  resemblance  to  the  thalloid  stem  of  Mar- 
chantia. 

There  are  thus  two  distinct  stages  in  the  life  history 
of  the  fern  :  one  is  known  as  the  vegetative,  asexual  or 
pteridoid  stage,  in  which  the  plant  consists  of  stem, 
roots  and  leaves,  and  produces  spores,  and,  strangely 
enough,  answers  to  the  sporogonium  of  the  moss ; 
the  other,  known  as  the  reproductive,  sexual  or  thal- 
loid stage,22  in  which  the  plant  consists  of  a  prothal- 
lium, on  which  the  reproductive  organs  are  borne,  and 
corresponds  to  the  leafy  plant  in  the  moss. 

These  reproductive  organs  are  quite  like  those  of 
Marchantia  and  Atrichum.  The  antheridia  consist 
originally  of  one  cell,  which  is  later  cut  up  into  a  cen- 
tral cell  and  several  parietal  ones.  The  contents  of 
the  central  cell  are  divided  into  a  number  of  small 
spherical  cells  in  which  are  formed  the  antherozoids. 
When  these  are  mature  the  parietal  cells  absorb  water 
and  burst  the  apical  one,  thus  permitting  the  anther- 
ozoids to  escape.  The  body  of  the  antherozoid  accord- 
ing to  Strasburger  23  is  to  be  regarded  as  the  proto- 
plasm of  the  nucleus  of  the  sperm  cell,  and  the  cilia  as 


22  Pteridoid  and  thalloid   are  terms  introduced  by    Underwood,    Our 
native  ferns  and  their  allies,  p.  35. 

23  Das  botanische   Practicum,  p.  455  ;  Sachs,    Text  book,   2nd   Eng. 
ed.,  p.  423. 


ADIANTUM  PEDATUM.  129 

the  peripheral  protoplasm  of  the  cell.  The  vesicle 
attached  to  the  hinder  coils  of  the  body  is  formed  from 
the  central  or  intermediate  contents  of  the  sperm  cell, 
and  usually  contains  some  starch  grains. 

The  archegonium  is  likewise  originally  a  single  cell 
of  the  prothallium,  which  by  subsequent  division  forms 
a  central  cell  containing  the  oosphere,  the  two  canal 
cells  whose  destruction  results  in  the  formation  of  the 
canal,  the  four  rows  of  neck  cells  and  the  layer  of  cells 
immediately  surrounding  the  central  cell.  ** 

The  conversion  of  the  two  canal  cells  into  mucilage, 
and  the  partial  expulsion  of  this  from  the  canal, 
entangles  and  allows  the  entrance  of  the  antherozoids, 
which  by  their  active  movements  work  their  way  to 
the  base  of  the  canal  and  penetrate  the  wall  of  the 
central  cell  in  which  lies  the  oosphere.  One  anthero- 
zoid  bores  its  anterior  end  into  the  germinal  spot  of 
the  oosphere  and  disappears  within  it,  probably  reach- 
ing the  nucleus.  The  others  lie  for  some  time  upon 
the  oosphere  and  are  gradually  absorbed,  only  one 
antherozoid  actually  penetrating  it.25 

The  result  of  the  fertilization  of  the  oosphere  is  the 
formation  of  a  new  plant,  which  remains  attached  to 
the  prothallium  on  its  under  side  for  some  time.  As 
the  young  fern  gradually  spreads  sufficiently,  and  is 
able  by  means  of  its  leaf  and  root  surface  to  gather 
nourishment  for  itself,  the  prothallium,  no  longer  use- 
ful, perishes. 

84  Cf.   Sachs,    I.e. 

*5  Strasburger,  op.  cit.,  p.  458. 


SCOTCH    PINE. 

Pinus  sylvestris  L. 

•  

PRELIMINARY. 

THE  Scotch  pine  is  a  species  commonly  planted  for 
ornament.  It  may  be  readily  recognized  by  the  follow- 
ing characters.  At  a  short  distance  the  tree  has  a 
grayish-green  color.  The  leaves  are  in  pairs,  five  to 
ten  centimeters  (two  to  four  inches)  long,  somewhat 
twisted,  covered  with  a  whitish  powder  which  can  be 
rubbed  off  with  the  fingers  and  to  which  the  peculiar 
color  of  the  tree  is  due.  The  cones  are  small,  about 
five  centimeters  (two  inches)  in  length,  the  free  ends  of 
the  scales  being  produced  into  conspicuous  protuber- 
ances, which  near  the  base  of  the  cone  are  recurved. 

The  Austrian  pine,  a  two-leaved  species  also  com- 
monly planted  for  ornament,  differs  from  the  preced- 
ing in  having  longer  leaves — from  ten  to  fifteen  centi- 
meters (four  to  six  inches)  in  length — with  a  dark  green 
color  without  any  of  the  powder.  The  cones  are  much 
larger  and  without  the  recurved  protuberances.  If 
the  Scotch  pine  can  not  be  procured  the  Austrian  will 
do  quite  well,  being  closely  similar  to  it  in  structure. 

The  flowers,  both  male  and  female,  should  be  col- 
lected in  spring  as  soon  as  the  male  flowers  begin  to 
scatter  their  pollen.  The  male  flowers  when  mature 


PIN  us  s  j  v  i  •/•:  s  TRIS.  1 3 1 

form  conspicuous  yellow  clusters  at  the  base  of  the 
young  shoots.  The  female  flowers  are  quite  inconspic- 
uous, in  small  oval  clusters  of  a  pinkish  color,  project- 
ing slightly  beyond  the  ends  of  the  young  shoots. 
The  tree  bearing  abundant  male  flowers  usually  bears 
few  female  ones,  and  vice  versa.  These  flowers  when 
collected  should  be  preserved  in  alcohol.  A  few  weeks 
later  the  two-year-old  cones,  which  will  be  found  just 
below  the  new  shoots,  should  be  collected  and  pre- 
served in  alcohol.  If  the  plant  is  to  be  studied  in 
spring  or  summer,  some  of  the  large  terminal  buds 
should  be  collected  in  the  late  autumn,  winter  or  early 
spring  preceding,  and  preserved  in  alcohol.  Leaves  and 
stems  should  be  gathered  about  the  first  of  July,  and 
preserved  in  alcohol.  Mature  cones  should  be  gathered 
in  winter  or  early  spring  and  allowed  to  dry,  care  being 
taken  to  prevent  losing  the  seeds,  which  will  shake  out 
on  drying. 

Fresh  leaves  and  stems  may  be  used  for  the  study 
of  the  gross  anatomy,  but  if  used  for  the  minute 
anatomy  it  is  well  before  cutting  sections  to  place  them 
in  alcohol  for  a  few  days  to  get  rid  of  the  resin  which 
exudes  and  gums  the  fingers  and  knife  unpleasantly. 
Before  cutting  sections  of  stems  or  leaves  which  have 
been  preserved  in  alcohol  and  before  dissecting  the  male 
and  female  flower  clusters,  it  is  well  to  place  them  for 
a  day  in  a  mixture  of  equal  parts  of  alcohol  and 
glycerine,  which  renders  them  somewhat  easier  to 
manipulate.  They  may,  however,  be  used  direct  from 
the  alcohol. 

The  requisites    for  the    complete  study  are  stems, 


f.J2  SCOTCH  PINE. 

leaves,  terminal  buds,  male  and  female  flowers,  year- 
old  and  two-year-old  cones,  preserved  in  alcohol ; 
mature  cones  and  seeds,  dry  ;  alcohol ;  potash  ;  glycer- 
ine ;  sulphuric  acid  ;  and  if  convenient,  magenta ; 
methyl  blue  ;  and  chlor-iodide  of  zinc. 

LABORATORY  WORK. 
GROSS  ANATOMY. 

A.  GENERAL  CHARACTERS.  Note 

1.  The  central   axis  or  stem;  its  few  main  branches  and 
numerous  very  short  dwarf  branches  *  bearing 

2.  Pairs  of  very  slender  elongated  green  needle  leaves, 

3.  The  scales  upon  the  stem,  those  covering  the  buds  at 
the  apex  of  the  stem  and  those  overlapping  the  bases  of 
young  leaves.     All  may  be  called  scale  leaves. 

4.  Near  the  base  of  the  young  shoots  in  some  specimens, 
a  number  of  oblong  (nearly   globular)  clusters  of  light 
yellow   bodies,  stamens,    the     male  flowers ;    in   other 
specimens,  one    or  two    small  oval   clusters  of  female 
flowers,  projecting  beyond  the  end  of  the  stem. 

B.  THE  STEM.     Examine 

1.  The  surface  of   a  year-old    shoot.     Note    the   scales 
covering  it,    especially  near  the  base    of    the    shoot. 
Compare  with  the  surface  of  older  stems  ;  note  the 
gradual  obliteration  of  the  scales. 

2.  The   arrangement   of   the    main    brnches?     Note  the 

1  The  terms  "  dwarf    branches  "  or    "dwarf    shoots"    will    be  used  to 
distinguish  these    from  the  main  branches    or    shoots.     (The  term  shoot 
includes  the  branch  with  its  leaves.) 

2  Best  seen  in  specime'ns  from  young  vigorous  trees.     If  possible   the 
student  should  study  the  tree  itself. 


PIN  US  SYLVESTRIS.  133 

number  of  branches  and  the  relative  vigor  of  terminal 
and  lateral*shoots.  Compare  also,  as  to  size,  the  buds 
found  in  clusters  at  the  apices  of  the  branches. 

The  arrangement  of  the  dwarf  branches.  Select  the 
straightest  and  most  vigorous  year-old  branches  for 
this  study.  Notice 

a.  The  position  of  the  branches  relative  to  the  scales. 
It.  Their  absence  from  certain  portions  of  the  stem. 

c.  Pull  out  the  pairs  of  leaves  from  fifteen  or  twenty 
consecutive  branches.     Stick  a  pin  at  the  base  of 
any  branch,  and   then  find   a  branch  that  stands 
directly  above   this  one.     Count  the  number   of 
branches  between  these,  including  the  first.     This 
number  will  be  equal  to  the  number  of  vertical 
ranks  in  which  the  branches  stand. 

d.  Make  a  diagram  in  the  following  manner,  to  show 
the  relative  position  of  the  branches  :  draw  lightly 
a  number  of  concentric  circles  about  three  milli- 
meters   apart    (the   number  should   be   twice   as 
many  as  the  number  of  vertical  ranks,  plus  one). 
Divide  the  outer   circle    by  as  many  equidistant 
points   as  there  are   vertical  ranks   of  branches. 
From  these   points  draw  radii,   lightly.     Take  a 
piece  of  straight  stem  about  ten  centimeters  long 
which  has  been  stripped  of  its  leaves.     Mark  the 
position  of  three  or  four  consecutive  branches  by 
pins,  so  placed  that  if  pressed  in  they  would  pass 
through  the  center  of  the  stem.    Fasten  the  lowest 
pin  securely.     Make  a  mark  on  the  outer  circle  at 
any  radius  to  indicate  the  position  of  the  branch 
marked   by   the  lowest   pin.     Erect   the  stem   at 
the  center  of  the  circles,  making  the  lowest  pin 
coincide   with   this   radius,   and    mark    the   next 


IJ4  SCOTCH  PINE. 

higher  branch  on  the  second  circle  at  the  radius 
with  which  its  pin  now  most  nearly  coincides.  Mark 
the  third  and  fourth  in  the  same  way.     Leaving 
the  lowest  pin  in  place,  move  the  pin  next  lowest  to 
the  next  higher  unmarked  branch,   and  mark  its 
position.       Repeat  this   until   all  the  circles   are 
filled,  numbering  each  branch  from  the  lowest  up. 
Studying  this  diagram  determine 
i.     The  arithmetical  difference  between  the  numbers 
of  the  branches  which  lie  on  the  same  radius, 
ii.     The  ^number  of  turns  made  by  a  spiral  line 
joining  successive  branches,   i,   2,   3,  4,  etc., 
until  it  reaches  a  branch  over  the  first, 
iii.     Find  a  fraction  which  will  express  the  part  of 
a  circle  intervening  between  any   two    suc- 
cessive branches. 

iv.  Note  that  the  numerator  of  this  fraction  ex- 
presses the  number  of  turns  made  by  the  spiral 
line,  and  the  denominator  the  number  of  ranks 
in  which  the  leaves  stand. 

4.    The  buds.     Notice 

a.  Their  position  and  relative  size. 

b.  Their  shape. 

c.  Their  structure.     Study 

i.  The  scales.  Carefully  strip  them  from  the  bud 
with  needles.  Note  particularly  the  character 
of  the  edges  and  the  differences  between  the 
apical  and  basal  portions.  After  removing  the 
brown  apical  portion,  the  green  basal  parts 
will  be  seen  closely  investing 

ii.  The  axis.  Bisect  longitudinally  the  portion 
of  the  bud  remaining.  Observe  in  the  center 
the  whitish  stem  or  axis,  tapering  gradually 


FIX  US  S  YL  VESTRIS.  135 

and  then  rapidly  to  a  point,  and  bearing  the 
thick-set  bases  of  the  bud  scales,  in  the  axils 
of  which  may  be  seen 

iii.  Secondary  buJs?  Take  out  one  of  these  buds 
carefully  and  dissect  it.  Note  the  scales  which 
cover  it.  By  cautiously  removing  these  the 
rudimentary  nccdle-lcares,  looking  like  two 
minute  knobs,  may  be  found,  apparently  at 
the  end  of  a  very  short  stem  to  which  the 
scales  were  attached. 

iv.     Make  drawings  showing  the  external  appear- 
ance and   structure  of  the  buds,  both  main 
and  secondary. 
d.      Compare  the  buds  with  the  branches.     Observe 

that  a  bud  is  simply  an  undeveloped  branch. 

5.  The  structure.  Cut  an  old  stem  square  across  to  study 
the  cut  surface.  Mount  also  a  transverse  section  of 
the  same.  Notice 

a.  A  central  yellowish  or  brownish  spot  of  irregular 
outline,  the  pith. 

b.  Surrounding  the  pith  a  zone  of  firm  tissue,  the 
wood.     Observe 

i.  The  concentric  masses  of  tissue,  growth  rings, 
the  number  depending  upon  the  age  of  the 
shoot  at  the  point  cut.  In  thin  parts  of  the 
section,  notice  the  difference  between  the 
central  and  peripheral  portions  of  any  growth 
ring, 
ii.  The  many  fine  radiating  lines,  the  medullary 

rays.     Note  the  extent  of  the  larger  ones, 
iii.     Many  small  scattered  openings,  the  resin  ducts. 

3  These  can  only  be  found  of  sufficient  size  to  dissect  in  buds  collected 
late  in  autumn  or  in  early  spring  just  before  they  begin  to  expand. 


I36  SCOTCH  PINE. 

iv.  In  some  sections  one  or  more  distinct  whitish 
bundles  passing  out  from  the  center  of  the 
stem.  Notice  that  a  continuation  of  the  cen- 
tral pith  occupies  the  center  of  each.  Observe 
the  relation  of  these  bundles  to  the  scars  on 
the  bark  indicating  the  position  of  former 
dwarf  shoots.  If  the  stem  be  four  or  more 
years  old,  note  that  the  bundles  stop  quite 
abruptly  at  the  close  of  the  second  year's 
growth. 

c.  All  the  part  outside  the  wood,  the  bark.     Distin- 
guish its  three  layers  : 

i.  The  inner  fibrous  layer,  whitish.  Notice  its 
appearance  and  thickness  relative  to  the 
whole  bark. 

ii.  The  middle,  green  layer.  Notice  the  large 
resin  ducts.  (In  fresh  specimens  note  the 
color,  consistence  and  odor  of  the  liquid  they 
exude.)  Compare  the  thickness  of  this  layer 
with  that  of  the  first. 

iii.  The  outer  brownish  layer,  except  in  quite  old 
stems  made  by  the  adherence  of  the  bases  of 
the  scale  leaves.  Note  its  relative  thickness, 
iv.  Strip  off  a  portion  of  the  bark.  The  three 
layers  may  be  easily  separated  with  the 
fingers.  Study  the  characteristics  of  each. 

d.  Bisect  the   stem  longitudinally.     On  the  cut  sur- 
face and  in  thin  sections  make  out  the  pith,  wood 
and  bark  ;    the  growth  rings,  medullary  rays,  and 
bundles  extending  toward  bases  of  former  leaf- 
branches,  in  the  wood  ;  the  three  layers  of  the  bark. 

e.  Make  drawings  of  the  transverse  and  longitudinal 
sections  to  show  completely  the  structure  of  the 
stem. 


PINUS  SYL  VESTRIS.  137 

6.    The  dwarf  shoots.     Carefully  break  one  from  the  stem, 
and  note 

a.  The  scales  (scale  leaves)  enwrapping  it  and  the 
bases  of  the  needle  leaves.  If  possible  compare 
these  scales  on  young  and  old  dwarf  shoots. 

It.     The  length. 

c.  The  very  small  rudimentary  terminal  bud  between 
the  leaves.  This  is  best  seen  on  the  dwarf  shoots 
from  young  vigorous  trees.  It  is  minute  or 
absent  on  others. 

C.   THE   LEAVES. 

1.  The  scale  leaves.     These  have  already  been  studied  as 
they  occur  on  the  dwarf  shoots  (B.  6.  a.)  and  in  the  bud 
(B.  4.  c.  i.).  Compare  the  scales  of  the  stem  with  those  of 
a  young  bud  and  notice  the  loss  of  the  deciduous  apex. 

2.  The  needle  leaves.     Note 

The  number  on  each  dwarf  branch. 
The  shape  and  apex  ;    also  the  shape  of  the  trans- 
verse section.     Draw  a  leaf. 

c.  The    color.     Compare    old    and  young  leaves  if 
possible. 

d.  The  texture ;    firmest   near  the  apex,  softer  near 
the    base,    due   to    basal  growth.     These    points 
are  especially  noticeable  in  young  leaves. 

e.  The  edges.     Draw  the  finger  from  the  apex  toward 
the  base.     Examine  with  a  lens. 

/.     The  surface.     Observe 

i.  That  it  is  faintly  whitened  (glaucous)  by  a 
powder  which  can  be  removed  by  drawing  the 
leaf  through  the  fingers  ;  best  seen  on  the 
flat  side. 


138  SCOTCH  PINE. 

ii.  The  longitudinal  rows  of  whitish  dots  on  both 
surfaces.  Cut  a  thin  slice  from  the  convex 
surface,  mount,  and  examine  by  transmitted 
light.  If  sufficiently  thin,  the  dots  will  now 
be  seen  to  be  minute  openings,  the  stomata  or 
breathing  pores.4 

g.      The   structure.      Cut    a    transverse   section   and 
examine  by  transmitted  light.     Notice 
i.     Occupying  the  center  an  oval  patch  of  whit- 
ish tissue,  the  fibro-vascular  region. 
ii.     Outside   the   central   whitish   area,   compact 
green  tissue,  mesophyll.     In  this  zone  notice  a 
dozen  or  more  openings,  the  resin  ducts. 
iii.     Enveloping  the  whole,  the  narrow  colorless 

cortical  area. 
iv.     Draw  the  section. 

Cut  a  longitudinal  section  parallel  to  the  flat  side.     Make 
out  the  same  regions  as  in  the  transverse  section. 

D.   THE  FLOWERS. 

i.    Male   or  staminate.     Carefully   break  off   one   of  the 
clusters. 

a.  Note  the  short  stalk  by  which  it  was  attached  to 
the  stem. 

b.  Note  that  the  cluster  is  made  up  of    numerous 
short-stalked  bodies,    the  stamens,  attached  to  an 
axis.     Each  stamen  consists  of  a  flat  scale  bearing 
on    the    inferior    surface   two   enlargements,  the 
pollen  sacs. 

c.  Burst  a  pollen  sac.     Note  the  innumerable  minute 
grains   of  pollen  which  escape. 


4  More  accurately,  the  external  chambers  of  the  stomata,  for  the  real 
stomata  are  deep  seated. 


PIN  US  SYL  VESTRIS.  1 30 

d.  Find   a  stamen   which   has   burst   spontaneously. 
Note  how  it  is  ruptured  (by  slits). 

e.  Note  the  arrangement  of  the  flowers?     They  are 
almost  sessile  and  crowded  on  an  elongated  axis 
forming   a   spike.     Notice    the    scale  subtending 
each  flower,  and  the  number  and   position  of  the 
scales  attached  to  the  short  stalk  of  the  flower. 

f.  Note  \h& position  of  the  flowers  ;  each  replaces  a 
branch  on  the  young  shoot. 

g.  Draw  a  stamen  showing  its  structure. 

2.    Female  or  pistillate.     Taking  a  single  cluster,  a  spike, 
notice 

a.     The  stalk,  peduncle,  by  which  it  is  attached  ;     its 

direction  ;  the  scales  on  the  peduncle. 
/>.     That  it  is  composed  of  two  kinds  of  scales  :   (i) 

thin,  the  bracts  ;  (2)  thick,  the  carpellary  scales. 
Dissect  out  a  single  bract ;  note 
i.     The  texture  and  shape. 
ii.     Draw  the  bract. 

Dissect  out  a  single  carpellary  scale  ;  note 
iii.     The  shape  and  texture. 
iv.     The  prominent  keel  on  the  upper  surface  in 

the  median  line. 

v.  Two  enlargements  on  the  superior  surface, 
near  the  proximal  end,  the  ovules.  Notice 
Disposition  of  the  ovules  and  the  large  ori- 
fice at  their  free  ends,  the  micropyle,  the 
integument  of  the  ovule  being  prolonged  into 
a  short  tube,  whose  right  and  left  sides  are 
still  further  produced  into  two  short  fila- 
ments. 

5  It  is  assumed  that  each  cluster  of  stamens  constitutes  a  single    flower. 


140  SCOTCH  PINE. 

vi.     Draw  a  scale  showing  all  these  points. 

c.  Difference  in  the  size  of  bracts  and  scales  in  differ- 
ent parts  of  the  same  cluster. 

d.  Position  of  the    cluster  ;     replacing    one  of  the 
main  branches. 

Examine  a  year-old  cone.     Bisect  it  vertically,  and  note 

e.  The  central  tapering  axis. 

f.  The  cut  edges  of  the  scales  and  bracts.     Observe 
the  relative  thickness  of  the  scales  at  their  proxi- 
mal and  distal  ends. 

g.  The  ovules  appearing  in  section  at  the  base  of  the 
scales. 

h.  Whether  the  scales  are  free  from  each  other  or 
adherent. 

/.       Draw  the  cut  surface. 

Dissect  out  a  scale  with  its  ovules.  Notice  the  many  scales 
with  abortive  ovules.  Bisect  a  well  developed  ovule  care- 
fully, through  the  micropyle.  Note 

j.      The  diminished  size  of  the  micropyle. 

k.      The  single  integument. 

I.  That  portion  inclosed  by  the  integument,  the 
nucellus. 

m.  Nearest  the  base  of  the  nucellus  (the  end  nearest 
the  micropyle  being  considered  the  apex)  a  large 
cavity,  the  embryo-sac,  partially  or  wholly  filled 
with  a  soft  substance,  the  endosperm. 

«.      Draw  the  cut  surface  of  the  ovule. 

E.  THE     FRUIT  (CONES).    Examining  a  mature  cone, 
notice 

1.  The  large  carpellary  scales,  making  the  bulk  of  the  cone. 
Observe  their  color,  above  and  below,  consistence,  shape 
and  markings  at  the  free  ends. 

2.  In  an  open  cone,  or  by  cutting  away  the  basal  third  of 


PIN  US  S  YL  VESTRIS.  1 4 1 

a  closed  cone,  the  smaller  bracts  subtending  the  carpel- 
lary  scales. 

Closely  applied  to  the  superior  surface  of  the  carpellary 
scales,  a  pair  of  thin  wing-like  scales,  each  bearing  at  its 
proximal  end  a  perfect  seed  or  an  abortive  oi'ule. 

The  seed.     Note 

a.  The  shape,  surface  and  markings. 

b.  At  the  pointed  end  notice  the  minute  opening,  the 
micropyle. 

c.  The  structure.     Bisect  the  seed  longitudinally  par- 
allel with  the  flatter  faces,  and  in  the  halves  make 
out 

The  firm  coat. 

The  inclosed  portion  consisting  of  two  parts  : 
(i)  the  young  plantlet,  embryo,  lying  in  the 
axis  ;  (2)  the  food  for  the  plantlet,  endosperm.* 

iii.     Note  the  position  of  the  embryo  with  respect 

to  the  micropyle. 
Take  another  seed  and  with  needles  dissect  off 

iv.  The  coat.  Notice  that  it  has  differentiated 
into  two  layers.  Compare  the  two  as  to 
color,  thickness  and  strength. 

Dissect  the  endosperm  carefully  from  the  embryo.     In  the 
latter  make  out 

v.     The  short  stem,  caulicle. 

vi.  The  six  divisions  arising  from  about  the  apex 
of  the  caulicle,  the  first  leaves,  cotyledons. 

vii.  A  minute  elevation  in  the  midst  of  the  coty- 
ledons, at  the  apex  of  the  caulicle,  the  rudi- 
mentary terminal  bud,  plumule.  (Not  easily 
seen.) 

6  The  endosperm  has  therefore  entirely  displaced  jthe  nucellus  originally 
surrounding  it.     (See  D.  2.  /.  and  m.) 


*42  SCOTCH  PINE. 

MINUTE  ANATOMY. 

A.  THE  STEM.     Cut  a  transverse  section  of    a    year-old 
stem,  examine  with  a  low  power  and  note 

1.  The    pith,     occupying    the     center    of    the    section. 
Observe 

a.  The  outline  of  the  pith. 

b.  In  some  sections  a  portion  extending  outward  to 
enter  a  dwarf  branch.     The   salient  angles  of   the 
pith  are  all  due  to  such  outward  extensions  at 
different  heights. 

c.  The  loose  arrangement  of  its  cells. 

2.  The  wood  (xyleni).     Observe 

a.  The  arrangement  of  the  cells. 

b.  The  openings  of  the  resin  ducts. 

c.  The  division  into  two  zones,  growth  rings. 

3.  The  cambium  ;  a  narrow,  cloudy  looking  zone,  bound- 
ing the  xylem.     (If  the  section  be  from  a  stem  gathered 
in  winter  or  early  spring,  the  cambium  zone  will  be 
indistinguishable.) 

4.  ^^  phloem  ;  of  compactly-arranged  cells,  with  a  whitish 
appearance. 

5.  The  cortical  parenchyma  ;  outside  the  phloem,  consisting 
of  large,  loosely-arranged  cells,  which  in  sections  of  a 
fresh  stem  contain  much  chlorophyll.     In  this  region 
note  the  large  oval  openings  of  resin  ducts. 

6.  Dark  lines  from  the  pith  to  the  cortical  parenchyma, 
the  medullary  rays. 

7.  The  edge  of  the  section.     The  cortical  parenchyma  is 
bounded  by  a  row  or  two  of  small  close-set  cells.     All 
the  tissue  beyond  this  belongs  to  the  bases  of  the  scale 
leaves,  which  cover  the  stem. 


SYLVESTRIS.  143 

Examine  with  a  high  power  and  study 

8.  T\i&  pith  parenchyma.      Note 

a.  The  shape  and  arrangement  of  the  cells  ;  the  modified 

shape  of  those  passing  out  to  a  dwarf  branch. 

b.  The  contents.     Test  with  iodine. 

9.  The  xylem.     Notice  that  the  salient  angles  of  the  pith 
divide   it  more  or  less  completely   into  wedge-shaped 
bundles.     Studying  one  of  these  wedges,  note 

a.  At  the  apex  one  or  two  resin  ducts.     Study  their 
structure,  noticing 

The  shape  of  the  opening. 
The  circle  of  rather  delicate  cells  lining  the 
duct,  the  secreting  layer.     Note   the  granular 
nucleus  in  each,  nearly  filling  the  cell. 
iii.     The  quite  irregular  circle   of  flattened   cells, 
with  longer  diameters  parallel  with  the  circum- 
ference, bounding  the  duct,  the  sheath. 

b.  Between  the  resin  duct  and  the  pith,  forming  the 
point  of  the  wedge,  a  group  of  several  spiral  and 
reticulated  vessels.     These  are    rather   difficult   to 
distinguish  from  the  wood  cells.     They  may  be 
recognized   by   their   slightly    thicker   walls,    the 
smaller    diameter    and    rounder    shape   of  their 
cavities.      On   staining  the  section  slightly  with 
magenta,  they  take  a  somewhat  deeper  color  than 
the  wood  cells.     After  the  section  has  lain  for  some 
time  in  glycerine  they  may  be  recognized  by  their 
greater  opacity. 

c.  Forming  the  bulk  of  the  xylem,  the  wood  cells  or 
fibers.     On  account  of  the  similarity  of  the  mark- 
ings (to  be  studied  later)  on  their  walls  to  those  on 
tracheae    or   vessels,    they  are   called   tracheides. 
Note 


144  SCOTCH  PINE. 

\.     Shape  and  arrangement. 
ii.     Their  emptiness. 

iii.  Their  thick  walls,  showing  in  thin  parts  of  the 
section,  a  middle  lamella. 

iv.  In  the  thinnest  part  of  the  section,  search  for 
places  where  the  radial  walls  7  of  contiguous 
cells  bow  away  from  each  other  like  two  watch 
glasses  placed  with  concavities  together. 
They  are  most  readily  found  in  the  youngest 
part  of  the  xylem.  In  the  most  favorable 
sections  these  bowed  walls  may  be  seen  to  be 
interrupted  at  their  points  of  greatest  diverg- 
ence thus  -O-.  These  are  sections  of  the 
bordered  pits  (further  described  at  A.  18.  b. 

iii.). 

v.  Compare  the  tracheides  of  the  outer  growth 
ring  with  adjacent  ones  of  the  inner  one. 

vi.  Wide  one-sided  bordered  pits  where  the 
tracheides  adjoin  the  cells  of  the  medullary 
rays. 

10.  The  cambium.     Note 

a.  The  radial  rows  of  rectangular,8  very  thin-walled 
cells,  passing  abruptly  on  the  one  hand  into  the 
xylem,  but  shading  almost  imperceptibly  on  the 
other  into 

11.  The  phloem.     Note  the  two  elements  which  compose 

it  : 

a.  Angular  thick-walled  cells  with  a  whitish  luster 
and  constituting  the  greater  part  of  the  phloem, 
the  sieve  cells.  In  favorable  sections  the  radial 

77.  e.,  those  lying  along  a  radius  of  the  stem. 
8  Very  apt  to  be  distorted  in  cutting. 


PIN  US  S  YL  VES  TRIS.  1 45 

walls  of  some  of  these  cells  will  be  found  perfor- 
ated by  clusters  of  very  fine  pits,  looking  like 
fine  parallel  lines  passing  across  the  wall.  These 
are  sections  of  \htsieveplates;  they  occupy  the 
same  relative  position  as  the  sections  of  the  bor- 
dered pits  of  the  tracheides.  Note  the  shape  of 
the  sieve  cells  next  the  cambium  and  next  the 
cortical  parenchyma. 

/>.  Near  the  periphery  of  the  sieve  tissue  an  inter- 
rupted row  of  cells  with  brown  or  yellow  contents 
in  which  are  strongly  refringent  crystals.  Near 
the  cambium  a  similar  row  of  cells,  larger  and 
rounder  than  the  sieve  cells  and  with  colorless  or 
slightly  yellowish  homogeneous  contents,  in  which 
a  small  crystal  or  two  may  sometimes  be  seen. 
These  two  broken  rows  of  cells  are  \hz phloem- 
parenchyma? 

12.  The  cortical  parenchyma.     Note 

a.  The  shape,  size  and  arrangement  of  the  cells.  Com- 
pare with  pith  parenchyma. 

b.  The  contents. 

c.  The  very  large  resin  ducts.     Compare  their  struct- 
ure with  those  of  the  xylem  (A.  9.  a.).     Note  the 
cells  of  the  sheath,  larger,  thicker-walled  and  not 
flattened  as  are  those  surrounding  the  ducts  in  the 
xylem  ;    the   secreting  cells,  similar  to  but  more 
numerous  than  those  of  the  xylem  ducts. 

13.  The   medullary   rays.     In   a  thin    part  of   the  section 
note 

a.      Their  extent,  from  pith   to   cortical  parenchyma. 

9  Can  be  brought  out  by  staining  with  chlor-iodide  of  zinc  and  better 
still  by  methyl  blue. 


146  SCOTCH  PINE. 

b.  The  shapes  of  the  cells  in  the  xylem  and  the  grad- 
ual transition  into  the  cortical  parenchyma. 

c.  The  contents  of  the  cells. 

14.  The   bases  of  the  scale   leaves.     (As  they    are    closely 
attached  to  the  stem,  and  the  lower  portions  not  dis- 
tinguishable from  it,  their  transverse  section  is  most 
conveniently   studied    at   this  time.)      Note   the  two 
layers  : 

a.  The  inner ;  cells  very  thin-walled  and  irregular, 
apt  to  be  distorted  in  cutting. 

b.  The  outer  ;  composed  of  one  or  two  rows  of  large 
cells,  sclerenchyma  (note  shape),  and  a  single  outer- 
most row  of  smaller  cells,  the  epidermis.     Note 

i.     The  thickening  of  the  outermost  wall  of  the 

epidermis. 

ii.     The  continuous  layer  covering  this  wall,  the 
cuticle. 

15.  Draw  a  part  of  the  section,  filling  in  sufficient  to  show 
the  structure  completely. 

Cut  a   longitudinal    radial  section  of  a  year-old    stem. 
Examine  with  a  low  power,  and  make  out 

1 6.  The  same  areas  as  seen  in  transverse  section,  in  this 
section  appearing  as  strips  : 

a.  The////?  j  its  regular  margins. 

b.  The  xylem.     Note 

i.     Patches*  of    transversely   placed    cells,    the 

medullary  rays. 
ii.     The  resin  ducts  j  showing  as  one  or  two  lighter 

streaks  in  the  xylem. 
iii.     The  two  growth  rings. 

c.  The  cambium  ;  a  very  narrow  whitish  strip. 

d.  'The  phloem  ;  compact  and  fibrous-looking. 

e.  The  cortical  parenchyma. 


PIN  US  SYL  VESTRIS.  147 

/.       r^\\t  scale  leaves. 
Examine  with  a  high  power.     Study 

17.  The  pith  cells.     Note 

a.      The  shape  and  arrangement. 

1 8.  The  xylem.     Note 

a.  Near  the  pith  parenchyma  a  cluster  of  spiral  and 
reticulated  vessels.      Notice    the    irregularity    and 
closeness  of  the  spiral  thickening. 

b.  The  tracheides,  making  the   bulk    of    the   xylem. 
Note 

i.     Their  shape.     Observe  their  ends. 

ii.     Their  thickened  walls. 

iii.  Their  markings,  bordered  pits.  In  the  young- 
est part  of  the  xylem  study  the  structure  of  one 
of  these  pits.  Observe  the  two  concentric 
circles  they  present.  Note  which  is  more  dis- 
tinct. Compare  with  transverse  section  and 
discover  the  cause  of  this  appearance.  The 
outer  circle  is  at  the  point  where,  in  section 
(see  diagram  at  A.  9.  c.  iv.)  the  arms  of  the 
Y  diverge  from  its  stem  ;  the  inner  is  the 
edge  of  the  opening  in  the  bowed  walls.  By 
examining  this  section  thoroughly,  chance 
sections  of  the  pits  may  be  found  which  will 
further  elucidate  their  structure. 

iv.  The  size  of  the  pits  compared  with  the  breadth 
of  the  fibers,  and  their  arrangement  on  the 
fibers. 

v.  The  large  thin  spots  on  the  walls  of  the  cells 
of  the  medullary  rays,  where  they  join  the 
adjacent  tissues. 

c.  Between  the  tracheides  and  the  spiral  vessels  a 
few   intermediate   cells   with  plain  pits  nearly  or 


148  SCOTCH  PINE. 

quite  as  large  as  the  bordered  ones  of  the  trach- 
eides.  By  focusing  carefully  the  walls  of  these 
cells  may  sometimes  be  seen  in  section. 

19.  The  cambium.     Note  the  shape  and  contents  of  the  cells. 
There   is  sometimes   difficulty  in  discovering  the  end 
walls  of  the  cambium  cells.     It  can  be  obviated  some- 
what by  examining  a  section  which  has  lain  in  glycerine 
for  a  few  hours.     Notice   particularly  the  delicacy  of 
the  walls. 

20.  The  sieve  cells.     Study 

a.  Their  shape  and  arrangement. 

b.  The  markings  on  their  walls  ;  round  or  oval  areas 
of  fine  perforations,  looking  like  minute  specks. 
Note  their  arrangement  ;  compare  with  that  of  the 
bordered  pits  on  the  tracheides. 

21.  Thz  phloem  parenchyma  ;  note  length  and  contents  of 
the  cells.10 

22.  The  cortical  parenchyma. 

a.  Study  the  shapes  and  contents  of  the  cells. 

b.  Notice  here  and  there  cells  which  seem  to  have 
been  divided  by  a  partition,  the  pair  still  retaining 
an  oval  shape. 

c.  The  large  intercellular  spaces. 

23.  The  medullary  rays.     Study  their  cells  in  the  cambium 
and  sieve  cell  regions. 

24.  The  resin  ducts.     (Their  longitudinal  structure  may  be 
studied  either  in  the  longitudinal  or  transverse  section 
of  the  stem,  the  latter  usually  showing  a  longitudinal 

10  Difficult  to  distinguish  without  staining  with  methyl  blue  or  chlor-io- 
dide  of  zinc. 


PLVUS  SYLVESTRIS.  149 

section  of  one  or  more  of  the  horizontal  branches  con- 
necting neighboring  ducts.  The  structure  is  most 
easily  made  out  in  those  of  the  xylem,  those  of  the 
phloem  being  too  large  to  allow  a  complete  section  to 
be  easily  obtained.)  Note 

a.  The  empty  cells  forming  the  sheath  ;    their  shape. 

b.  The  secreting  parenchyma  cells  lining  the  duct  ; 
shape  and  contents. 

25.  The  bases  of  the  scale  leaves.     Note 

a.  The  delicate  thin-walled  cells  forming  their  inner 
portion. 

b.  The  rather  thick-walled  cells,  sclerenchyma,  form- 
ing the  outer  part. 

c.  The  very  thick-walled  outer  row,  the   epidermis, 
with  thickly  pitted  walls. 

d.  The  very  thick  cuticle. 

e.  The  contents  ;  note  color. 

26.  Draw  a  portion  of  the  section,  showing  all  the  above 
points. 

Cut  a   longitudinal  tangential  section,  passing  through 
the  wood.     Examine  with  a  high  power,  and  note 

27.  The  cut  ends  of  the   medullary  rays,  wedged  between 
the  fibers  of  the  xylem.     Notice 

(7.     The  number  of  rows  of  cells  in  the  thickness  and 
height  of  each  ray. 

b.  The  thin  parts  of  the  walls  corresponding  to  the 
pits  (see  A.  18.  b.  v.). 

c.  Make  a  drawing  of  one  of  the  rays,  showing  also 
a  few  adjacent  tracheides. 

28.  The  numerous  sections,  in  different  directions,  through 
bordered  pits.     Study  these  sections  further,  if  necessary 
to  an  understanding  of  the  structure  of  the  pits. 


150  SCOTCH  PINE. 

29.  The  very  tapering  ends  of  the  tracheides. 

Cut  transverse  and  longitudinal  sections  of  a  young  stem 
collected  at  flowering  time.  Examine  with  a  high  power, 
and  compare  with  similar  sections  of  the  older  stem.  Notice 
the  walls  and  contents  of  the  cells  of  the  several  tissues 
and  particularly 

30.  The  distinctness  of  the  spiral  and  reticulated  vessels. 

31.  The  deep  indentations  of  the  margin  of  the  stem  in 
transverse  section,    marking  the  breadth  of  the  scale 
leaves. 

32.  The  simple  epidermal  and  hypodermal  tissues  consti- 
tuting the  bases  of  the  scale  leaves. 

Strip  off  the  brown  apical  portions  of  the  bud-scales  from 
a  winter  bud  and  bisect  it  longitudinally  a  little  to  one  side 
of  the  center.  Cut  a  series  of  longitudinal  sections  as  uni- 
formly thin  as  possible,  until  the  center  of  the  stem  has  been 
passed.  Mount  every  section,  treat  with  potash  and  exam- 
ine with  a  low  power.  Search  for  the  section  which 
includes  the  center  of  the  axis.  It  may  be  recognized  by 
the  conical  shape  of  the  apex.  Note 

33.  The  central  axis  or  stem..    Observe  the  arrangement 
of  the  cells. 

34.  The  buds  on  the  side  of  this  axis.     Notice 

a.  The   large  scale   (base  of  bud  scale)   subtending 
each. . 

b.  The  central  rounded  mass  of   cells,  an  undevel- 
oped dwarf  branch,  covered  in  by  scales.     Search 
for  a  bud  whose  central  part  shows  three  rounded 
protuberances.     These  are  the  two  leaves  with  the 
terminal  bud  of  the  dwarf  branch  between  them. 
Draw. 


PIN  US  S  YL  VES  THIS.  1 5  I 

35.  The  conical  apex,  growing  point,  of  the  axis.     Notice 
the  scales  which  cover  it. 

Examine  with  a  high  power.     Study  both  the  growing 
leaves  and  the  apex  of  the  stem.     Note 

36.  The  shape  of  the  cells,  which  in  these  regions  are  cap- 
able of   division  and  are   collectively  known   as   the 
primary  meristem. 

37.  A  short  distance  behind  the  growing  apex,  the  cells  of 
the    primary    meristem   become    differentiated,    some 
becoming  elongated  and  fusiform  and  others  forming 
the  spiral  vessels.    Trace  them  further  and  further  from 
the  growing  point  and  notice  that  the  differentiation 
constantly  increases. 

38.  On  the  sides  of  the   section,  just  behind  the  conical 
point,  one  or  two  elevations,  the  apices  of  the  axes  of 
lateral    buds    of    the   succeeding  season.     Draw  the 
apex. 

B.  THE  LEAVES.  Cut  a  transverse  section  of  one  of 
the  older  needle  leaves  below  the  middle.  Examine  with  a 
low  power,  and  note 

1.  The  shape  of  the  section. 

2.  The  three  distinct  regions  it  presents  : 

a.  The  narrow  outer  cortical  region,  whitish  in  color. 

b.  The  central  oval  fibro-vascular  region,  bounded  by 
a  distinct  chain  of  cells,  the  bundle  sheath. 

c.  Between  these  two  regions,  a  zone  of  green  (green- 
ish even  in  alcoholic  specimens)  parenchyma,  the 
mtsophyll. 

3.  The  number  and  position  of  the  resin  ducts. 

4.  Make  a  sketch  of  the  section. 


152  SCOTCH  PINE. 

Examine  with  a  high  power,  and  study 

5.  The  epidermal  cells.     Note 

a.  The  very  thick  walls,  their  cavities  nearly  or  quite 
obliterated.     The  outer  layers   of  this  thickening 
are  cuticularized. 

b.  The   cuticle,    quite   thick  and   dipping  as  a   thin 
wedge  between  the  cells. 

c.  The  crack-like  pits  radiating  from  the  cavity. 

d.  The  enlargement  of  the  cell  which  forms  the  corner 
of  the  leaf. 

e.  The    stomata.      Study    their    structure    carefully, 
noting 

i.  The  peculiar  shape  of  the  epidermal  cells 
above  the  stoma,  the  outer  wall,  about  as 
thick  as  the  adjacent  cells  of  the  epidermis, 
prolonged  upward  to  form  a  ridge  overarch- 
ing the  outer  chamber  of  the  stoma.  Observe 
the  cavity  of  these  cells,  much  larger  than 
those  of  adjacent  cells.  At  the  bottom  of  the 
outer  chamber, 

ii.  The  guard  cells,  their  shape  and  the  thicken- 
ing of  their  outer  walls. 

iii.  The  large  intercellular  space  beneath  the 
guard  cells,  the  inner  chamber  of  the  stoma. 

6.  The  usually  single,  in  places  double  or  triple,  row  of 
small  cells  underneath  the   epidermis,  the  hypoderma, 
Note 

a.  The  shape,  and  the  thickness  of  walls. 

b.  Where  the  greatest  number  of  cell-rows  occurs. 

c.  The  well-defined  middle  lamella. 

d.  That  the  hypoderma  is  interrupted  at  each  stoma. 

7.  Draw  a  stoma  with  a  few  of  the  adjacent  epidermal 
and  hypodermal  cells. 


PIN  US  SYLVESTRIS.  153 

8.  The  mesophyll.     Note 

a.  The  shape  of  the  cells,  and  the  number  of  rou>s 
between  the  hypoderma  and  bundle  sheath. 

b.  The   infolJings   of  the   wall,  dividing   the   cavity 
into  recesses.     Observe  the  position  of  the  most 
prominent   of  these    infoldings  in  the  outermost 
row    of    mesophyll  cells.      Observe    occasionally 
(usually   near  a   stoma)  branched  cells.      Deter- 
mine the  relation  of  these  to  the  cells  with  simple 
infoldings. 

c.  In  fresh  specimens,  the  abundant  chlorophyll. 

d.  The  resin    ducts ;    compare  their    structure   with 
those  of  the  stem.     Notice  the  thick  walls  of  the 
cells  of  the  sheath. 

9.  Draw  a  few  mesophyll  cells  showing  also  a  resin  duct. 
10.    The  fibro-vascular  region.     Study 

a.  The  bundle   sheath ;    shape  and    contents    of  the 
cells. 

b.  The  two  masses  of  small  cells,  the  fibro-vascular 
bundles,  somewhat   separated  from  each  other  and 
obliquely  placed.     Note  the  well-marked  division 
into  two  areas  : 

i.  The  xylem,  next  the  flat  side  of  the  leaf, 
consisting  of  spiral  and  reticulated  ves- 
sels and  tracheides,  arranged  in  radial  rows. 

ii.  The /£&£»!,  next  the  convex  side  of  the  leaf, 
consisting  chiefly  of  undeveloped  sieve  cells. 

iii.  The  radial  rows  of  parenchyma  (like  medul- 
lary rays),  passing  through  both  xylem  and 
phloem. 

iv.  In  the  xylem  area,  occasionally  a  poorly 
developed  resin  duct. 


154  SCOTCH  PINE. 

v.     Draw  one  of  the  bundles. 

c.  Between  the  bundles  and  more  or  less  encircling 
them,  especially  next  the  convex  side  of  the  leaf, 
fibrous  tissue  consisting  of  large  thick-walled   cells 
with  small  cavities. 

d.  On  the  side  of  the  bundle  pair  toward  the  flat 
side  of  the  leaf,  large  thin-walled,  mostly  empty  cells. 

e.  Filling  the  remainder  of  the  fibre-vascular  region 
and   entirely   encircling   the  parts  named,    large 
tracheides  resembling  the  preceding,  but  with  more 
or  less  conspicuous  contents,  and  walls  marked 
with  bordered  pits.     Compare  the  markings  with 
those  of  the  tracheides  of  the  stem,  studying  both 
face  and  section  views. 

f.  Draw  a  few  cells  of  each  tissue  named  outside  the 
bundles. 

Cut  a  longitudinal  section  through  the  central  part  cf  the 
leaf.     Examine  with  a  high  power,  and  study 

11.  The  epidermis.     Note 

a.  The  shape  of  the  cells.     Unless  the  section  be  quite 
thin,  the  epidermis  will  appear  as  a  continuously 
thickened  border  of  the  section.     The  end  walls  of 
the  cells  are  hard  to  make  out,  even  in  the  best 
sections. 

b.  The  irregular  cavity,  and  innumerable //&  which 
perforate  the  thickening  layers. 

c.  If  a  number  of  sections  be  made,  one  or  more  will 
traverse    a    line  of  stomata.     Note  the  shape  of 
the  outer  chamber,  the  shape  of  the  guard  cells, 
and  of  the  intercellular  space  below. 

d.  Draw  a  stoma  and  the  adjacent  cells. 

12.  Underlying  the  epidermis,  the  elongated  sclerenchyma 
cells,  the  hypoderma.     In  sections  passing  through  a 


PIN  US  S  YL  VESTRIS.  1 5  5 

line  of  stomata,  note  the  absence  of  any  hypoderma, 
except  short  cells  between  the  guard  cells  of  adjacent 
stomata. 

13.  Draw  a  few  cells  of  epidermis  and  hypoderma. 

14.  The  mesophyll.     Note  how  loosely  it  is  arranged,  with 
an  intercellular  space  between  the  rows  of  cells,  enlarg- 
ing under  each  stoma.     Note  also  the  shapes  of  the 
cells,  the  apparent  absence  of  infoldings  in  this  view, 
and  the  number  of  cells  in  each  row  between  the  bun- 
dle sheath  and  hypoderma.     The  determination  of  the 
latter   point   will   need   close   inspection   and    careful 
focusing.     The  infoldings  seen   in  transverse   section 
are   now   seen   as   apparent   partitions  increasing  the 
apparent  number  of  cells  above  the  actual.     In  places 
none  of  these  false  partitions  occur,  and  the  real  number 
of  cells  may  be  easily  noted.    Draw  a  few  rows  of  meso- 
phyll cells. 

15.  The  resin  ducts  ;  note  the  sheath  cells,  elongated  and 
thick  walled  ;  the  secreting  cells,  with  thin  wavy  walls 
and  prominent  nuclei.     Draw. 

1 6.  The  fibro-vascular  region.     The  various  tissues  of  this 
region  appear  as  strips  in  this  section. 

a.  The  bundle  sheath  ;  a  row  of  elongated  cells  next 
the  mesophyll.  Draw. 

If.  The  tracheides,  on  both  sides  of  the  bundles  ; 
note  the  shape  and  markings  of  the  cells. 

c.  Note  the  change  in  shape  where  this  tissue  adjoins 
the  fibrous  tissue,  the  cells  becoming  much  elon- 
gated. Draw,  showing  both  forms. 

J.  The  fibrous  tissue  ;  greatly  elongated  thick-walled 
fibers  with  tapering  ends,  next  the  tracheides. 
Draw. 


156  SCOTCH  PINE. 

<?.      Next  the  xylem,  large  thin-walled  mostly  empty 

cells. 

/.      The  phloem  j   consisting  of  thick-set,    very   long 
cells,  with  slightly  oblique  ends,  usually  crowded 
with  protoplasm    and    containing    large    nuclei. 
Draw. 
g.      The  xylem  j  note 

i.     Tracheides  like  those  of  the  stem  but  poorly 

developed,  with  few  markings, 
ii.     Spiral  vessels    like  those  of  the  stem  ;    var- 
iously placed  with   respect  to  the  tracheides. 
Cut  the  thinnest  possible  slice  from  the  surface  of  an  old 
leaf   and   then   cut   a   thin    section   from   the   same  place. 
Mount  both  with  the  outer  surfaces  upward  and  examine 
with  a  high  power.     Studying  the  first,  the  slice  of  epidermis, 
note 

17.  The  arrangement  of  the  stomata. 

18.  The  two  kinds  of  epidermal  cells,  those  lying  near  and 
in  a  line  of  stomata  and  those  lying  between  the  lines 
of  stomata  ;  observe  the  shapes.     In  the  former  note 
the  ridge  formed  by  the  upturned  edges  of  the  six  cells 
which  bound  the  stoma.11     If  this  cannot  be  readily 
made  out,  treat  the  specimen  with  potash  and  observe 
again  in  a  few  minutes.     Draw  a  few  cells  of  each. 

In  the  tangential  section  from  beneath  the  epidermis, 
note 

19.  The  cut  ends  of  the  mesophyll  cells  ;  shape  and  arange- 
ment.     Draw. 


11  The  student  should  not  mistake  the  peripheral  border  of  the  ridge 
for  the  outer  wall  of  the  six  cells.  The  cells  mentioned  are  quite  large, 
the  central  ones  extending  from  one  stoma  to  another  and  the  others  us- 
ually half  that  distance. 


PIN  US  SYLVESTRIS.  157 

20.  The  guard  cells  of  the  stomata  also  may  usually  be 
seen.     Draw. 

Cut  a  transverse  section  of  the  base  of  a  young  leaf,  col- 
lected at  flowering  time. 

21.  Compare  with  the  transverse  section  of  an  older  leaf. 

Note  the  presence  of  protoplasm  in  almost  all  the 
tissues,  completely  filling  the  cells.  Clear  with  potash. 
Compare  carefully  each  tissue  with  the  mature  form, 
noticing  particularly  the  lack  of  differentiation  of  the 
tissues,  especially  in  the  fibre-vascular  region. 

Mount  one  of  the  scales  which  enwrap  a  young 
leaf.  Examine  with  a  low  power,  and  note 

22.  The  shape  and  arrangement  of  the  cells. 

23.  The  fringe  at  the  free  end  of  the  scale.     Notice  of 
what  each  hair  of  the  fringe  consists. 

Cut  a  transverse  section  of  these  scales  by  cutting  a 
transverse  section  at  the  base  of  a  pair  of  young  leaves. 
The  sections  of  the  scales  will  float  off  when  the  leaf  section 
is  placed  in  water.  Note 

24.  The  number  of  cell  rows  i-n  thickness  ;  the  shape  of 
the  cells  and  thickness  of  the  walls  of  some  of  them. 

25.  A  trace  of  a  fibro-vascular  bundle  in  the  center  of  some 
of  the  thicker  scales. 

C.  THE  FLOWERS. 

i.  The  stamens.  Tease  out  a  portion  of  the  wall  of  an 
empty  pollen  sac.  Examine  with  a  high  power,  and 
note 

a.  The  shape  of  the  cells. 

b.  The  beaded  appearance  of  the  walls. 


158  SCOTCH  PINE. 

c.  Draw  a  few  cells. 

Place  an  entire  male  flower,  from  whose  pollen  sacs  the 
pollen  has  all  escaped,  between  pieces  of  pith  and  cut  trans- 
verse sections  of  the  cluster.  Chance  sections  of  the  walls 
of  the  pollen  sac  will  thus  be  obtained.  Examine  with 
a  high  power,  and  note 

d.  The  number  of  cells  in  thickness. 

e.  The    reticulated   thickening  of  the  lateral  walls, 
which  gives  rise  to  the  beaded  appearance  seen  in 
the  surface  view.     Draw. 

Break  open  two  or  three  pollen  sacs  and  mount  the 
pollen.  Examine  with  a  high  power,  and  note  in  each 
grain 

/.      The  three  lobes  into  which  it  seems  to  be  divided  : 
a   central  one,  the  essential  part    of  the  grain  ; 
attached  to  this  two  vesicular  protrusions  or  wings 
with  wrinkled  surfaces. 
g.      In  the  central  lobe  make  out 

i.  The  double  wall  of  the  cell  ;  the  outer  part, 
the  extine,  rather  thick  and  having  its 
slightly  roughened  external  portion  expanded 
into  the  vesicular  wings  ;  the  inner,  the  inline, 
very  thick  and  transparent. 

ii.  The  contents  (treat  with  iodine)  ;  protoplasm, 
abundant  starch,  and  sometimes  one  or  two 
clear-looking  drops  of  oil. 

iii.  The  division  into  two  cells  :  one  very  large, 
containing  the  starch  and  oil  ;  the  other  very 
small,  at  the  end  of  the  central  lobe  furthest 
from  the  wings,  best  seen  when  the  grain  is 
lying  on  its  side. 

Treat  the  iodine-stained  pollen  grains  just  examined  with 
75^  sulphuric  acid.  Press  gently  on  the  cover  glass  with 


7Y.V C'S  SVL  VESTRIS.  1 5 9 

the  handle  of  a  dissecting  needle.     Examine  with  a  high 
power,  and  note 

//.      The  empty  extine,  distorted  by  the  pressure,  and 

stained  yellow. 
/.      The  intine,  blue,  much  swollen,  and  either  empty 

or    still    containing    the   protoplasm,  starch  and 

oil.     If  empty  the  smaller  cell  can  usually  be  well 

seen. 
j.       The  yellow  protoplasm,  dark  blue  starch  grains  and 

clear  oil  drops,  escaped  from  some  of  the  pollen 

grains. 
k.      Draw  a  pollen  grain,  showing  all  its  parts. 

2.  The  cone.  Take  a  cluster  of  female  flowers,  bisect  it 
longitudinally,  and  from  one  of  the  halves  cut  longi- 
tudinal radial  sections.  Treat  with  potash.  Examine 
with  a  low  power,  and  selecting  a  section  which  has 
passed  through  an  ovule,  note 

a.  The  central  axis  bearing  the  bracts,  each  subtend- 
ing a  carpellary  scale,  to  whose  upper  surface  the 
oi'itle  is  attached. 

/>.      The  body  of  the  ovule,  nucellus,  surrounded  by 

c.  The  integument,  which  is  prolonged  beyond  it. 

d.  The  continuity  of  the   nucellus  and  integument 
with  the  carpellary  scale. 

e.  The  orifice  in  the  integument  at  its  proximal  end, 
the  micropyle. 

f.  Draw,  showing  the  above  points. 
Examine  with  a  high  power,  and  notice 

g.  That  the  cells  of   the  nucellus,  integument  and 
scale  are  all  alike  parenchymatous  and  filled  with 
protoplasm. 

Dissect  out  a  carpellary  scale  from  the  central  part  of  a 
year-old  cone  and  cut  a  series   of  longitudinal    sections, 


160  SCOTCH  PINE. 

including  about  the  middle  third  of  the  ovule.  Mount  all 
the  sections,  and  treat  with  potash.  Examine  with  a  low 
power,  and  note 

h.      The /#/-£$•  of  the  ovule  :  integument,  nucellus  and 

micropyle. 

/*.  The  parts  of  the  scale  :  the  scale  proper  and  the 
wing  of  the  seed.  Notice  that  the  tissues  of  the 
scale  are  continuous  with  those  of  the  wing  and 
ovule  ;  a  faint  trace  of  the  coming  lines  of  separa- 
tion may  however  be  detected. 

/  The  differentiation  of  the  tissues  of  the  scale  into 
two  kinds  :  the  one  of  densely  packed  small  cells 
forming  an  outer  layer  with  deeper  seated  fibers  ; 
the  other  of  looser  larger  cells,  forming  the  inter- 
mediate portion. 

k.      The  differentiation  of  the  integument  of  the  ovule 
into  two  layers,  the  outer  of  densely  packed  small 
cells,  the  inner  of  looser  larger  cells. 
/.       The  discoloration  of  the  apex  of  the  nucellus. 
/;/.     The  presence  of  a  large  cavity  in  the  nucellus,  the 
embryo-sac,  filled  with  a  delicate  transparent  tissue, 
endosperm. 
Examine  with  a  high  power,  and  note 

n.      That  the  body  of  the  nucellus  is  almost  entirely 

displaced  by  endosperm  cells. 

o.      The  wall  of   the  embryo-sac  ;    wavy  and  usually 
broken    away  from    the    remaining    cells   of   the 
nucellus  in  cutting  the  section. 
/.      The  endosperm  cells;  observe 
i.     The  delicacy  of  the  walls. 
ii.     The  contents  ;  thready  protoplasm  and  a  very 

large  round  nucleus  with  a  nucleolus.  • 
iii.    Draw  a  few  endosperm  cells. 


PI  XL  TS  SYL  VESTRIS.  l6l 

t/.  Near  the  outer  end  "  of  the  embryo-sac,  one  or  two 
much  larger  cells,  the  archegonia  or  corpuscula." 
Observe  the  distinct  row  of  endosperm  cells, 
smaller  than  the  others,  which  surrounds  the  arche- 
gonia. 

r.  Occasionally  one  or  two  pollen  grains  having 
shed  the  extine,  may  be  found  in  the  micropyle, 
and  still  more  rarely,  some  may  be  found  which 
have  begun  to  emit  their  tubes. 

s.  Make  a  diagram  of  the  ovule  and  all  its  parts, 
together  with  the  wing  and  carpellary  scale. 

ANNOTATIONS. 

The  Scotch  pine  raises  a  strong  tall  stem  above  the 
ground  for  the  purpose  of  better  exposing  its  leaves 
and  fruits  to  the  air  and  sunlight.  This  habit  is  cor- 
related with  the  excessive  development  of  the  fibro- 
vascular  system,  which  includes  all  the  tissues  of  the 
mature  stem,  with  the  exception  of  a  trifling  amount 
at  its  center  and  circumference. 

Not  only  is  there  provision  for  continued  growth  in 
length  by  the  formation  of  terminal  buds,  as  in  Adi- 
antum,  but  there  is  also  provision  for  growth  in  diameter. 
A  part  of  the  tissue,  from  which  the  fibro-vascular 
bundles  are  formed,  lying  between  the  xylem  and 
phloem,  retains  the  power  of  division  and  by  annual 
increase  in  the  number  of  cells,  chiefly  in  a  radial 
direction,  the  thickness  of  the  bundle  is  increased.  The 
difference  in  the  size  and  shape  of  the  cells  added  to 
the  xylem  in  the  spring  and  autumn  gives  rise  to  the 

12  /.  e.,  the  end  nearest  the  micropyle. 

13  Frequently  not  well  developed  at  this  time. 


1 62  SCOTCH  PINE. 

so-called  annual  or  growth-rings  which  can  be  seen  in 
the  wood. 

The  scales  which  cover  the  stem,  though  called  by 
the  same  name  as  the  brown  chaffy  appendages  to  the 
stem  of  the  fern,  are  not  trichomes  like  them,  but 
leaves.  In  addition  to  these  scale  leaves,  which  per- 
form only  slightly  the  function  of  true  leaves,  there 
are  the  needle  leaves,  upon  which  the  foliage  work 
chiefly  depends.  The  delicate  scales  which  enwrap 
the  bases  of  the  needle  leaves  are  not  trichomes,  but 
leaves,  as  the  rudimentary  fibro-vascular  bundle  in 
them  shows. 

The  different  mode  of  arrangement  of  the  scale 
leaves  (and  consequently  of  the  dwarf  branches)  upon 
the  terminal  and  lateral  shoots  is  worthy  of  notice. 

Concerning  the  homology  of  the  parts  of  the  male 
and  female  flowers,  more  especially  the  latter,  there 
has  been  and  still  is  much  controversy.  It  is  gener- 
ally admitted  that  each  cluster  of  stamens  constitutes  a 
single  male  flower.  The  scales  which  bear  the  pollen 
sacs  on  their  under  sides  are  homologous  with  leaves, 
as  is  shown  by  their  position  and  anatomical  characters 
and  occasionally  in  teratological  changes.14  Moreover, 
the  flower  is  subtended  by  a  bract,  and  the  floral  axis 
bears  several  (usually  three)  bractlets  below  the 
stamens.16 

As  first  announced  by  Robert  Brown  le  the  ovule  in 
the  pines  and  their  allies  is  naked,  /.  e.  it  is  not  sur- 
rounded, as  in  the  vast  majority  of  flowering  plants, 

14  Eichler,  Blttthendiagramme,  p.  59. 

15  Cf.  Strasburger,  Das  botanische  Practicum,  p.  469. 

16  Appendix  to  Botany,  Capt.  King's  Voyage,  iv,  p   103. 


PIN  US  S  YL  VESTRIS.  1 63 

by  an  ovary ;  whence  the  entire  group  of  plants  having 
this  character  are  called  gymnosperms.  Latterly,  there 
has  been  much  controversy  as  to  the  nature  of  the 
carpellary  scale  and  whether  the  ovule  is  really  or 
only  apparently  naked.  The  latter  question  involves 
the  determination  of  the  nature  of  the  integument 
of  the  ovule.  It  is  held  on  the  one  hand  that  the 
ovule  consists  of  nothing  but  a  nucellus,  and  that 
the  coat  surrounding  this  nucellus  is  the  homologue 
of  the  wall  of  the  ovary.  On  the  other  hand  it  is 
contended  that  this  structure  is  the  true  integu- 
ment of  the  ovule  and  that  the  scale  which  bears 
the  ovule  is  an  open  carpel  or  pair  of  carpels.17  In 
the  laboratory  directions  we  have  adopted  the  latter 
view,  calling  the  organ  which  bears  the  ovules  a  carpel- 
lary scale.  This  carpellary  scale  is  theoretically  "  com- 
posed of  two  leaves  of  an  arrested  and  transformed 
branch  from  the  axil  of  the  bract,  which  are  in  the 
normal  manner  transverse  to  the  subtending  bract, 
:  *  *  each  bearing  an  ovule  on  its  dorsal  [as  to 
position,  upper]  face;  the  two  are  coalescent  into  one 
by  the  union  of  their  posterior  edges,  and  the  scale 
thus  formed  is  thus  developed  with  dorsal  face  pre- 
sented to  the  axis  of  the  cone,  the  ventral  to  the  bract. 
It  is  therefore  a  compound  open  carpel  composed  of 
two  carpophylls.  This  character  of  being  fructiferous 
on  the  back  or  lower  side  of  the  leaf  occurs  in  no  other 
phaenogamous  plants."  18 

11  References  to  extensive  literature  of  this  discussion  may  be  found  in 
Gray,  Struct.  Bot.,  p.  272.  For  a  general  statement  of  views  and 
summing  up  of  argument  see  Eichler,  Sind  die  Coniferen  gymnosperm 
odernicht?  Flora,  1873,  p.  241.  Consult  also  Sachs,  Text-book,  2nd 
Eng.  ed.,  footnote,  p.  507.  From  references  in  these  places  the  whole 
subject  may  be  traced. 

18  Gray,  Struct.  Bot.,  p.  273,  footnote. 


164  SCOTCH  PIN£. 

As  soon  as  the  male  flowers  begin  to  scatter  their 
pollen  to  the  wind,  the  axis  of  the  young  cones  elon- 
gates, separating  the  carpellary  scales  sufficiently 
to  allow  the  pollen  to  be  blown  in  between  them, 
and  to  slide  down,  guided  by  the  keel,  to  the  pro- 
longations of  the  integument.  These  prolongations 
subsequently  roll  inward,  thus  carrying  any  grains 
which  may  have  become  attached  to  them  to  the  apex 
of  the  nucellus.  After  this  process  of  pollination  is 
accomplished  the  bracts  cease  to  develop  and  like- 
wise the  now  useless  keel.19 

The  minute  anatomy  of  the  Scotch  pine  presents 
many  points  of  considerable  interest. 

True  tracheary  tissue  is  formed  only  at  the  peri- 
phery of  the  pith,  where  a  cluster  of  spiral,  reticulated 
and  pitted  vessels  occurs  at  the  apex  of  each  woody 
wedge. 

The  tissue  of  the  wood  is  almost  exclusively  made 
up  of  tracheides,  on  whose  radial  walls  are  bordered 
pits.  As  these  walls,  originally  thin  and  plain,  increase 
in  thickness  irregularly,  a  part  of  the  thickening  on 
each  side  of  the  primary  wall  grows  away  from  it 
to  form  the  arched  "  border "  of  the  small  aperture 
which  remains.  For  some  time  the  primary  wall 
remains  as  a  membrane  separating  the  two  cells  ; 
when  finally  this  is  destroyed  there  is  free  communica- 
tion between  the  contiguous  cells. 20 

The  thin  delicate  walls  of  the  cambium  allow  great 
activity  of  the  contained  protoplasm,  which  results 

19  Strasburger,  op.  cit.,  p.  476. 

20  Cf.    Strasburger,  Bau   und    Wachsthum   der  Zellhaute,  p.  43,  taf. 
iii.     For  figures  cf.  Sachs,  Text-book,  p.  25. 


PIXUS  S  YL  VESTR1S.  1 65 

in  the  formation  by  division  of  many  new  cells.  The 
older  cells  on  the  axial  side  become  gradually  trans- 
formed into  the  tracheides  and  those  on  the  peripheral 
side  into  the  elements  of  the  phloem. 

Replacing  the  tracheides  of  the  xylem  are  the  sieve 
cells  of  the  phloem.  The  radial  walls  of  the  larger  cells 
have  on  them  clusters  of  small  perforations  which  are 
known  as  sieve  plates  or  disks.  These  sieve  plates  are 
homologous  with  the  bordered  pits  on  the  tracheides  of 
the  xylem."  At  a  little  distance  from  the  cambium 
they  become  covered  with  a  homogeneous  substance, 
the  so-called  callus  plate,  which  completely  interferes 
with  the  function  of  the  sieve  cells.  Though  this  callus 
plate  is  subsequently  dissolved,  the  sieve  cells  never 
regain  their  activity,  the  protoplasm  having  by  this 
time  disappeared  from  them.  " 

The  cells  with  brown  and  crystalline  contents  are 
the  true  phloem  parenchyma.  A  single  row  of  them 
is  formed  each  season,  so  that  the  age  of  the  stem  may 
be  determined  by  these, "  as  also  by  the  growth  rings 
of  the  xylem. 

The  general  arrangement  of  the  tissues  of  the  bun- 
dles is  in  contrast  to  that  in  the  fern.  The  xylem  and 
phloem  here  lie  side  by  side,  whence  the  bundle  is 
known  as  collateral.  " 

The  rigidity  of  the  leaves  of  the  pine  is  due  to  the 
thickening  of  the  cells  of  the  epidermis,  together  with 
the  development  of  the  layer  or  layers  of  hypodermal 
fibers. 

21  Strasburger,  Das  botanische  Practicum,  p.  143. 

2U  Strasburger,  op.  cit.,  p.  147. 

83  Strasburger,  op.  cit.,  p.  146. 

94  Russow,  Vergl.  Untersuch.,  fide  DeBary,  Comp.  Anat.,  p.  319. 


1 66  SCOTCH  PINE. 

Although  the  guard  cells  of  the  stomata  appear  at 
first  sight  to  be  deeper  seated  than  the  epidermis, 
observation  teaches  that  they  have  been  pushed  down 
by  the  crowding  over  them  of  the  adjacent  epidermal 
cells,  and  here,  as  always,  belong  to  the  epidermis. 
This  is  confirmed  by  examining  younger  stomata. 

The  partial  partitions  by  which  the  mesophyll  cells 
are  distinguished  are  explained  by  Sachs"  as  intru- 
sive foldings  due  to  local  growth  of  the  wall  at  the 
point  where  the  fold  occurs.  Corry  28  however  asserts 
that  there  is  no  real,  but  only  apparent  ingrowth, 
which  is  caused  in  this  way :  when  the  cells  are  still 
small  their  nuclei  are  attached  to  the  protoplasm  lining 
the  wall  by  delicate  protoplasmic  strands  one  or  more 
of  which  at  a  later  period  become  converted  into  cel- 
lulose thus  attaching  the  nuclei  firmly  to  the  wall. 
When  the  cell  enlarges  these  points  are  firmly  held 
near  the  nucleus.  Since  some  of  the  strands  soon 
break,  many  of  the  infoldings  are  shallow  while  others 
holding,  cause  deep  infolding.27  The  purpose  of  these 
infoldings  is  considered  by  Haberlandt  to  be  to 
secure  a  greater  surface  on  which  to  display  the 
chlorophyll  bodies.  Corry  says  of  them  :  "  They  per- 
form at  all  events  a  very  obvious  and  noteworthy 
function  in  forming  the  intercellular  spaces  beneath 
the  stomata  in  Pinus,  and  in  producing  air  channels 

25  Text-book,  2nd  Eng.  ed.,  p.  74. 

26  On  some  points  in  the  structure  and  development  of  the  leaves  of 
Pinus  sylvestris. — Proc.  Camb    Phil.  Soc.,  iv  (1883),  p.  344  et  seq. 

27  Similar  infoldings  in  leaves  of  Elymus  Canadensis  and  other  grasses 
are   described  by    Kareltschikoff   (Bull.   Imp.   Soc.    Nat.    Moscow,    xlt 
[1868],    p.    180)   and  in    Caltha  palustris,    Anemone   nemorosa  and   a 
number  of  other  plants  by  Haberlandt  (Oester.  Bot.  Zeit,  xxx  [1880], 
P-  305). 


PIN  US  S  YL  VESTRIS.  1 6  7 

between  the  cells  forming  the  several  rows  of  palisade 
tissue."28 

The  four  bundles  of  each  pair  of  leaves  have  the 
normal  orientation,  the  xylem  portions  all  facing  a 
common  center  and  the  phloem  the  periphery.  The 
imbedding  of  the  bundles  in  a  mass  of  colorless  tissue 
surrounded  by  a  sheath  is  common  among  the  pines 
and  their  allies. 

In  this  central  tissue  many  of  the  cells  are  tracheides 
(see  fig.  7),  as  pointed  out  in  the  laboratory  part  ;  they 
are  arranged  in  a  special  manner  and  are  characteristic 
of  ConiffTG*  These  tracheides  during  the  activity 
of  the  leaf  contain  water,  80  and  hence  have  been,  called 
transfusion  tissue  by  H.  v.  Mohl31  and  others. 

The  existence  of  occasional  poorly  developed  resin 
passages  in  the  xylem  of  the  leaf  bundles  is  to  be  noted, 
as  it  has  been  denied  by  Corry33  and  Van  Tieghem.33 
(See  fig.  7  r). 

In  comparing  the  reproduction  of  the  pine  with 
that  of  the  fern  and  earlier  forms  we  find  advances  of 
much  interest.  In  the  fern,  as  in  the  moss  and  liver- 
wort, the  spore  grows  into  a  structure,  which  bears 
the  reproductive  organs.  In  the  moss  and  liver- 
wort this  sexual  or  thalloid  stage  comprises  by  far  the 
larger  part  of  the  life  cycle,  while  the  asexual  stage 
(the  so-called  fruit)  is  small  and  quite  unable  to  lead 
an  independent  existence.  In  the  fern  the  thalloid 

88  Op.  cit.,  p.  355. 

*9  Cf.  DeBary,  Comp.  Anat.,  p.  378  et  seq. 

30  Strasburger,  op.  cit.,  p   234. 

31  Bot.  Zeitung,  1871,  No.  i,  2. 

32  Op.  cit.,  p.  359. 

33  Ann.  Sci.  Nat.,  Ser.  V,   xvi  (1872),  p.  189. 


1 68  SCOTCH  PINE. 

stage  is  much  reduced,  although  still  green  and  able 
to  maintain  itself  for  a  limited  time,  while  the  asexual 
stage  is  the  conspicuous  part  of  the  plant,  in  fact  the 
only  part  usually  noticed,  except  by  students  and  fern 
propagators. 

From  the  fern  to  the  pine  is  too  great  a  step  to  be 
well  understood  without  considering  some  intermediate 
type.  Some  species  of  Selaginella  would  answer  this 
purpose  admirably,  and  it  is  to  be  regretted  that  no 
species  is  sufficiently  common  in  this  country,  either 
wild  or  cultivated,  to  permit  the  introduction  of  direc- 
tions for  its  study  in  this  manual.  It  must  therefore 
suffice.to  mention  one  feature  of  Selaginella  indispens- 
able for  a  clear  understanding  of  the  subject  in  hand. 

Selaginella,  instead  of  having  only  one  sort  of  spores, 
as  in  the  ferns  and  liverworts,  has  two,  one  small  (micro- 
spores),  the  other  large  (macrospores).  When  these 
spores  vegetate,  the  prothallium  from  the  smaller  one 
bears  the  male  organs  (antheridia),  and  that  from  the 
larger  the  female  organs  (archegonia).  A  very  marked 
feature  is  that  the  prothallia  are  greatly  reduced,  so 
much  so  in  fact  that  they  never  leave  the  spore  or 
become  green,  and  the  one  from  the  smaller  spore  is 
even  reduced  to  a  single  small  cell.34 

To  return  to  pine,  we  shall  find  that  the  reduction  of 
the  sexual  stage  or  prothallium  is  carried  a  step,  and 
quite  a  long  step  further  than  in  Selaginella,  while  the 
asexual  stage  is  augmented  in  the  same  proportion. 
The  latter  in  fact  is  the  pine  tree — the  whole  plant  one 
would  naturally  say.  It  must  be  borne  in  mind  that  in 

34  For  further  description  see  Bessey,  Botany,  p.  385  ;  Sachs,  Text- 
book, p.  468. 


PLVUS  SYLVESTRIS.  169 

the  fern  the  asexual  plant  produces  spores,  and  that  in 
Selaginella,  a  more  advanced  type,  it  does  also,  but  of 
two  sorts.  Does  the  pine  likewise  produce  spores  ? 
Certainly,  although  we  have  so  long  called  them  pollen, 
that  we  are  inclined  to  forget  their  true  relation, 
which  would  be  better  indicated  by  the  term  pollen 
spores,  used  by  DeBary.35  These  pollen  spores  cor- 
respond to  the  microspores  of  Selaginella,  and  like 
them  have  the  prothallium  reduced  to  one  or  a  few 
cells,  but  unlike  them  do  not  produce  antherozoids. 
This,  however,  is  a  matter  of  adaptation.  Wherever 
there  is  water  to  transport  the  fertilizing  element 
from  the  male  to  the  female  organs,  it  is  usually 
an  active  body  (antherozoid),  as  in  Adiantum,  Atri- 
chum  and  Marchantia,  with  an  exception  in  Spirogyra, 
while  if  it  must  be  transported  through  the  air  or  the  inte- 
rior of  plant  tissues  a  tube  leads  from  the  antheridium 
to  the  archegonium  as  in  Microsphaera  and  Cystopus. 
Pine  like  other  flowering  plants  has  the  spores  carried 
bodily  through  the  air  in  order  to  bring  them  into 
proximity  to  the  female  element,  then  a  tube  (pollen 
tube)  develops,  which  connects  the  male  and  female 
organs.  Turning  now  to  the  female  part,  which  cor- 
responds to  the  macrospore  of  Selaginella,  it  (now  called 
the  embryo-sac)  is  found  so  greatly  reduced  that  it 
never  leaves  the  place  in  the  mother  plant  where 
formed.  The  prothallium  is  represented  by  the  pri- 
mary endosperm.  The  archegonia  themselves  are 
much  simplified  as  might  be  expected.  They  arise 
from  superficial  cells  of  the  endosperm  (prothallium). 

35  Morph.  u.  Biolog.  d.  Pilze,  Mycet.  u.  Bacterien,  1884,  p.  140. 


170  SCOTCH  PINE. 

Within  each  is  a  large  nucleated  germ  cell  or  oosphere, 
the  part  to  be  fertilized. 

The  process  of  fertilization  is  as  follows :  The 
pollen  grains  having  been  lodged  in  the  micropyle 
upon  the  apex  of  the  nucellus,  the  extine  is  burst  and 
slipped  off  by  the  swelling  of  the  intine  and  its  con- 
tents. By  a  local  growth  the  intine  extends  into  a 
tube  into  which  the  contents  of  the  larger  cell  pass  by 
a  streaming  movement,  the  smaller  cell  remaining 
inert.  This  pollen  tube  pushes  its  way  slowly  between 
the  cells  of  the  nucellus  until  it  reaches  the  germ  cell 
in  the  embryo-sac.  Shortly  afterward  a  nucleus  almost 
as  large  as  that  of  the  germ  cell  appears  below  the  end 
of  the  pollen  tube.  It  is  to  be  supposed  that  it  has 
passed  through  the  wall  of  the  tube,  and  it  is  to  be 
regarded  as  homologous  with  the  body  of  an  an- 
therozoid.  The  two  nuclei  fuse  into  one,  which  passes 
to  the  end  of  the  germ  cell  opposite  the  neck  where  it 
gives  rise  to  several  four-celled  layers,  one  above 
another,  the  lower  four  of  which  form  the  beginning 
of  the  embryo.36  This  process  of  fertilization  requires 
in  Pinus  sylvestris  a  little  more  than  a  year  between 
the  beginning  of  the  growth  of  the  pollen  tube  and 
the  consummation. 

The  fertilized  germ  cell  grows  at  once  into  the  young 
plantlet  (embryo),  as  in  the  fern,  but  at  this  stage, 
unlike  the  fern,  it  stops  for  awhile,  and  in  the  passive, 
well  protected  condition  of  a  seed  may  pass  a  long 
period  before  it  resumes  its  growth.  This,  again,  is  a 
special  adaptation.  All  the  plants  heretofore  con- 
sidered are  fully  equipped  for  the  dispersion  of  each 

36  Cf.  Strasburger,  op.  cit,  p.  481  et  seq. 


PINUS  S  YL  VES TRIS.  1 7 1 

succeeding  generation  through  their  sexual  or  asexual 
spores,  or  the  division  of  the  vegetative  members.  In 
the  pine  the  young  plantlet  is  developed  before  leaving 
the  parent,  and  were  it  to  continue  to  grow  would 
either  live  wholly  upon  the  parent,  or  be  brought  into 
such  close  competition  with  it,  that  the  species  would 
speedily  become  extinct.  Therefore,  to  provide  for 
the  proper  dispersion  of  the  offspring,  the  young 
plantlet  is  suitably  protected,  and  provided  with  food 
for  its  first  growth  when  again  resuming  its  develop- 
ment, separated  from  the  parent,  and  wafted  away  by 
the  wind  in  the  utmost  security. 

This  is  one  of  the  most  characteristic  features  of  the 
higher  plants,  from  which  they  might  better  have  been 
named  seed-bearing  plants,  than  flowering  plants. 

It  is  also  worthy  of  notice  that  the  primary  endo- 
sperm which  is  formed  during  the  first  year  of  the 
fruit,  and  on  which  the  archegonia  arise,  is  subsequently 
destroyed  by  the  deliquescence  of  the  cell-walls ;  and 
from  the  protoplasm  thus  set  free  there  is  produced 
in  the  spring  of  the  second  year  what  may  be  called 
secondary  endosperm  which,  with  the  growing  embryo, 
fills  up  the  embryo-sac  and  displaces  the  most  of  the 
tissue  of  the  nucellus.87 

37  Cf.  Sachs,  Text-book,  2nd  Eng.  ed.  p.  521. 


FIELD    OATS. 

A  vena  sativa  L. 

PRELIMINARY. 

THE  cultivated  grass  known  as  oats  is  too  familiar  to 
need  description.  Specimens  should  be  collected  at 
the  time  when  some  flowers  of  the  panicle  are 
expanded  and  others  are  yet  in  the  bud.  This  plant 
begins  to  bloom  shortly  after  the  panicle  is  liberated 
from  the  sheath.  The  time  of  blossoming  is  so  little 
marked  by  external  changes  that  there  is  great  danger 
that  specimens  will  be  collected  too  late.  Care  should 
be  taken  in  lifting  the  plants  from  the  ground  not  to 
detach  the  empty  grain  from  which  it  grew,  which  will 
almost  certainly  be  done  if  the  plants  are  pulled  up. 
They  should  be  dug  and  the  dirt  shaken  gently  from 
the  roots,  which  may  be  further  cleaned  by  washing. 

The  requisites  for  the  complete  study  of  the  plant 
are  entire  plants,  preserved  in  alcohol ;  a  handful  of 
threshed  oats  ;  alcohol ;  magenta  ;  potassic  hydrate  ; 
and  iodine. 

LABORATORY  WORK. 
GROSS  ANATOMY. 

A.    GENERAL     CHARACTERS.     Note   the  four  parts 
of  the  plant  : 


A  VENA  SATIVA.  173 

1.  The  roots. 

2.  The    upright    main    axis,   the    stem,   with    numerous 
branches  near  the  top. 

3.  The  lateral  appendages  of  the  stem,  the  leaves. 

4.  The  surface  appendages  on  the  roots  and  leaves,  the 
trichomes,  in  both  instances  extremely  minute. 

B.    THE  ROOTS.     In  a  plant  which   has   the   emptied 
grain  from  which  it  grew  still  attached,  note 

1.  The  small  group  of  roots  arising  from  one  end  of  the 
grain,  the  strongest  of  which  is  fat  primary  root. 

2.  The  stem  emerging  from  the  other  end,  the  first  inter - 
node  of  the  stem. 

3.  At  a  certain  point,1  the  second  node  of  the  stem,  a  whorl 
of  secondary  roots. 

4.  At  one  or  two  succeeding  nodes,  a   like  whorl  of  sec- 
ondary roots. 

5.  Make  a  diagram,  showing  the  position  of    the  roots 
and  their  relation  to  the  lower  part  of  the  stem. 

Cut  a  transverse  section  of  one  of  the  large  secondary 
roots.     Examine  by  transmitted  light.     Note 

6.  The  round  central  spot  of  firmer  tissue,  \.\\z  fibro-vas- 
en  Jar  bundle.     The  openings  in  it  are  the  larger  vessels. 

7.  The  loose,  pith-like  cortical  portion. 

8.  The  root-hairs,  attached  to  the  edge. 

9.  Draw. 


1  Known  to  agriculturists  as  the  "  tillering  point."  The  length  of 
this  first  internode  depends  to  a  considerable  extent  on  the  depth  of  plant- 
ing the  seed. 


174  FIELD  OATS. 

Strip  off  the  cortical  portion  of  one  of  the  large  secondary 
roots.     Notice 

10.  The  slender,  strong  fibre-vascular  axis  which  remains. 

Examine  some  plants  three  or  four  days  old,  which  have 
been  grown  on  the  surface  of  wet  blotting  paper.     Note 

11.  The  position  of  roots  and  stem  with  respect  to  the 
grain. 

12.  The  abundant  root-hairs.     Notice  their  relative  length 
on  different  parts  of  the  root,  and  where  absent. 

13.  The  opaque  tip  of  the  root  covered  by  the  conical  root- 
cap. 

C.  THE  STEM.  Notice  that  it  is  completely  encased  by 
the  sheathing  bases  of  the  leaves.  Uncover  a  portion  of 
the  stem  by  removing  one  of  the  leaves  and  its  sheath,  and 
note 

1.  Its  shape,  and  polished  surface. 

2.  Its  nodes  and  internodes.     Bisect  the  stem  longitudinally 
through  a  node  and  a  portion  of  an  internode.     Note 

a.  The  solid  node  forming  a  partition  between  the 
cavities  of  the  internodes. 

b.  Draw. 

Look  through  the  split  stem  at  a  bright  light,  and  note 

3.  The  numerous  threads,  traversing  the  stem  lengthwise, 
the  fibro-vascular  bundles. 

Cut  a  transverse  section  and  examine  by  transmitted  light, 
and  note 

4.  A  very  firm,  more  opaque  external  layer,  the  cortical 
layer.     Notice  its  variable  thickness. 

5.  In  the  cortical  layer,  pairs  of  darker  spots.     These  are 
clusters  of  chlorophyll-bearing  cells. 


ATENA  SATITA.  175 

6.  The  remainder  of  the  section  made  up  of  large  rounded 
cells,  parenchyma,  scattered  through  which  are 

7.  Masses  of  firmer  tissue,  the  fibro-vascular  bundles,  each 
having  three  or  four  openings,  the  vessels. 

8.  Draw  the  section. 

Cut  a   number  of  longitudinal  sections  ;  in  them  make 
out 

9.  The  denser  cortical  portion. 

10.  The  more  transparent  parenchyma. 

11.  The  fibro-vascular  bundles. 

12.  In  a  section  not  passing  through  a  fibro-vascular  bun- 
dle,   the    strip   of   darker   chlorophyll-bearing   tissue 
under  a  very  narrow  cortical  layer. 

13.  Draw  a  section,  showing  as  much  as  possible  of  the 
structure. 

D.  THE  LEAF.     Note 

1.  Its  sheathing  base.     Observe  the  extent   of  stem  cov- 
ered by  each  sheath. 

2.  The  split  in  the  sheath  ;  its  position  and  extent. 

3.  On  the  upper  surface  at  the  point  where  the  sheath 
ceases,    a   thin   membranous    outgrowth,  the    ligule. 
Notice  its  shape  and  apex.     Draw. 

4.  The  place  of  attachment  of  the  leaves. 

5.  The  remainder  of  the  leaf,  the  blade.     Note 

a.  Its  shape. 

b.  The  numerous  veins  ;  their  direction  and  relation 
to  the  ridges. 

c.  The  green  tissue  (bleached  by  alcohol)  between 
the  veins,  the  mesophyll. 


I76  FIELD  OATS. 

Cut  a  transverse  section  of  the  blade,  and  note 

6.  The  variable  thickness  of  the  leaf. 

7.  The  sections  of  the  fibre-vascular  bundles. 

8.  On  the  upper  edge,  large  cells  between  the  ridges,  the 
hygroscopic  cells,  which  cause  the  leaf  to  roll  when  dry. 

E.  THE  FLOWERS. 

i.    The  arrangement  of  the  flowers,  anthotaxy.     Note 

a.  The  central  stem  of  the  flower  cluster,  the  main 
axis  of  inflorescence. 

b.  Its  lateral  branches,  secondary  axes.     Notice  their 
relative  lengths. 

c.  That  some  of  the  secondary  axes  are  branched, 
others  not,  thus  constituting  a  panicle. 

d.  Make  a  diagram  of  the  mode  of  branching. 

e.  That   each  ultimate   branch   bears    not  a   single 
flower,  but  a   cluster   of   three   (sometimes  two) 
flowers,   a   spikelet,    at  the   thickened   extiemity. 
The   entire    inflorescence  is   thus    compound,   a 
panicle  of  spikelets. 

Detach  a  spikelet,  and  note 

/.  Two  bracts  at  the  base  of  the  spikelet,  completely 
inclosing  the  flowers,  the  empty  glumes.  Notice  the 
position  of  these  glumes  with  respect  to  each 
other  and  their  points  of  attachment.  Detach 
them,  and  note 
i.  Their  shape. 

ii.     The  parallel  veins,  nerves ;   the  number     in 
each  glume,  the  termination  above,  the  deli- 
cate cross  (anastomosing)  veinlets. 
iii.     Draw. 


A  VEX  A   S A 'I  IV A.  177 

g.      The  three  flowers  inclosed  by  the  empty  glumes  ; 

their  relative  size2  and  position  on 
//.      The  flattened  axis  on  which  they  are  borne,  the 

rhachis  of  the  spikelet. 
/'.       The  tufts  of  minute  hairs  at  the  base  of  the  lowest 

flower. 
j.       Draw  a  spikelet,  showing   the  empty   glumes  and 

flowers  separated  from  one  another. 

2.    The  structure  of  the  flowers.     Detach  the  lowest  flower 
in  the  spikelet.     Note 

a.  The  bract,  flowering  glume,3  which  almost  incloses 
the  flower.     It  sometimes  bears  a  long  bristle-like 
appendage  or  awn  on    its    outer    surface  ;    note 
position  when  present.     Detach  this  bract  entire, 
and  note  the  size,  shape,  surface,  texture,  notched 
apex  and  number  of  nerves.     Draw. 

From  another  flower  cautiously  detach  the  flowering 
glume  by  cutting  and  tearing  it  away  piece  by  piece,  leav- 
ing only  a  bit  of  its  base,  being  careful  not  to  injure 

b.  rY\\&  flower  proper.     Observe 

i.  A  large  bract-like  body,  the  palet,4  its  infolded 
margins,  shape,  nerves,  and  the  presence  and 
position  of  the  trichomes  on  its  outer  surface  ; 
contrast  it  with  the  flowering  glume.  Draw  ; 
also  make  a  diagram  of  a  transverse  section 
at  its  middle. 

ii.  Two  small  bract-like  bodies,  the  lodicules, 
situated  between  the  edges  of  the  palet.  Ob- 
serve their  shape  and  texture.  Draw. 

7  The  third  is  rudimentary  and  lies  close  to  the  inner  side  of  the  upper 
flower. 

8  Called  the  lower  palet   in  most  systematic  works. 
4  Called  the  upper  palet  in  most  systematic  works, 


178  FIELD  OATS. 

iii.    The  three  similar  sta mem.  Examine  one  care- 
fully, and  note  three  parts  : 

a.  The  slender  thread,  filament,  carrying  at 
its  apex 

/?.  A  two-lobed  body,  the  anther ;  note 
the  deep  groove  lengthwise  of  each  lobe, 
and  the  point  of  attachment  of  the  fila- 
ment. 

y.  Tear  open  an  anther,  or  examine  one 
which  has  burst,  and  notice  the  cavities 
contain  ing  pollen  ;  the  color  and  powderi- 
ness  of  the  grains. 

d.      Draw  a  stamen, 
iv.     The  hairy  body  in  the  midst  of  the  stamens, 

the  pistil.     Note  its  three  parts: 

a.  The  large,  top-shaped  part  at  the  base, 
clothed  with  white  hairs,  the  ovary. 

/?.  The  two  thread-like  bodies  arising  from 
the  top  of  the  ovary,  the  styles. 

y.  The  numerous  branches5  of  the  styles 
arranged  like  the  barbs  of  a  feather,  the 
stigmas. 

d.      Draw  a  pistil. 

Cut  a  pistil  in  two  longitudinally   between  the   styles, 
and  notice 

£.      The  thick   but   delicate  wall  of  the  ovary. 

2,.  The  ovule  of  denser  tissue  closely  adher- 
ing to  it,  and  mostly  occupied  by 

77.  A  cavity,  filled  when  growing  with  the 
transparent  endosperm,  which  cannot  now 
be  easily  detected.  In  this  cavity  notice 

5  If  hidden  by  many  adherent  pollen  grains,  brush  them  off  with  a  camel's- 
hair  brush. 


A  VENA  SATIVA.  179 

0.  The  early  stage  of  the  young  plantlet  of 
the  seed,  the  embryo. 

1.  Illustrate  with  diagram. 

Compare  with  this  flower  the  second  and  third  flowers  of 
the  spikelet.  Note,  in  the  latter,  the  absence  of  the  inner 
organs,  leaving  only  the  flowering  glume,  palet,  and  some- 
times the  stamens. 

F.  THE  FRUIT.  Study  ripe  oats  which  have  been 
threshed  or  shelled  out  in  the  hand.  Strip  off  the  chaff 
(flowering  glume  and  palet)  which  incloses  the  fruit.  Note 

1.  The  white  hairs  which  cover  it,  especially  at  the  upper 
end. 

2.  The  longitudinal  groove  ;  its  position  as  to  the  palet. 

3.  The  scar  at  the  base  of  the  grain  opposite  the  groove, 
marking  the  position  of  the  plantlet  within. 

Cut  across  the  middle  of  a  grain,  and  note 

4.  The   depth  of  the   groove,    and   the    uniform   floury 
contents  ;  test  with  iodine. 

5.  That  the  wall  of  the  ovary  and  the  coats  of  the  ovule 
have  become  so  closely  united  and  thin  as  to  be  indis- 
tinguishable, thus  constituting  the  fruit  a  caryopsis  or 

grain. 

6.  Draw  the  section. 

From  a  soaked  grain  carefully  remove  the  "  skin  "  (the 
wall  of  the  ovary  together  with  the  seed  coats)  on  the  side 
opposite  the  groove,  from  the  lower  end  to  the  middle. 
There  will  then  be  seen  a  face  view  of 

7.  The  embryo.     Note 

a.      The  large  elongated-triangular  body  forming  the 


I  So  FIELD  OA  TS. 

upper  part  of  the  embryo,  the  cotyledon  or  scutellum. 

b.  The  pointed  lower  extremity,  the  root  sheath. 

c.  Near  (below)  the  center  of  this  face  of  the  embryo, 
a  minute  bud,  \he  plumule. 

d.  Just  below  the  base   of  the  plumule,  a  very  short 
stem,  the  caulicle? 

e.  Draw  the  embryo  as  it  lies  exposed. 

Bisect  a  grain  longitudinally  through  the  groove.  Mount 
also  a  thin  section  from  the  cut  surface.  Note 

f.  The  scutellum,   with  its  back  against  the  starchy 
part  of   the  seed,  its  face  just  under   the  "skin" 
at  the  upper  part  of  the  embryo. 

g.  The  plumule,  on  the   face  of  the  scutellum,  at  the 
upper  end  of 

h.  The  caulicle;  easily  recognized  as  the  whitish 
part  where  the  scutellum  and  plumule  merge. 
At  its  lower  extremity  is 

/.      The  root,  a  small  rounded  point,  over  which  is 
/.      The  root-sheath,  which  forms  the  lower  extremity 

of  the  embryo. 
k.      Draw  the   section. 

Take  a  series  of  transverse  sections  from  the  bottom  of 
the  grain  upward.  Examine  the  successive  cut  surfaces  and, 
comparing  with  the  longitudinal  secti®n,  determine  the 
various  parts  seen,  root-sheath,  root,  caulicle,  plumule, 
scutellum.  Draw  those  which  show  the  section  of  root  and 
root-sheath,  and  the  section  of  plumule  and  scutellum. 

MINUTE  ANATOMY. 

A.  THE  ROOTS.  Cut  a  transverse  section  of  one  of  the 
lateral  roots  at  a  little  distance  from  the  stem.  Examine 
with  a  low  power,  and  note  the  two  regions  : 

6  111  defined  and  difficult  to  see. 


A  TEN  A  SATIVA.  181 

1.  The  cortical,  thin-walled  cells. 

2.  The  fibro-vascular,  thick-walled  cells. 
Examine  with  a  high  power,  and  note 

3.  The   thin-walled  epidermis.     Observe  its  irregularity, 
and  the  mode  of  attachment  of  the  root-hairs.     Draw. 

4.  The    cortical  parenchyma,    with    sclerenchyma    either 
intermixed,  or  in  older  roots  forming  an  outside   layer. 
Draw. 

5.  The  bundle  sheath  ;  the  relative  thickness  of  outer  and 
inner  walls  ;  the  pits.     Draw. 

6.  The  fibro-rasciilar  bundle.     Study 

a.  The  smaller  thick-walled  cells  constituting  most 
of  the  bundle. 

b.  The  vascular  tissue  ;  four  to  six  (sometimes  more) 
\ax%t  pitted  vessels  symmetrically  disposed.  Between 
each  of  these  and  the  bundle  sheath  (also  some- 
times near  the  center)  a  dozen  (more  or  less)  of 
smaller  pitted  vessels. 

c.  Numerous   channel-pits   in    all    the   thick-walled 
cells. 

d.  Draw  a  portion  of  the  bundle. 

Cut  a  longitudinal  section  of  the  same  root.     Examine 
with  a  high  power,  and  note 

7.  The  epidermal  cells.     Observe  the  bases  of  root-hairs, 
and  their  relations  to  the  epidermal  cells.     Draw. 

8.  Elongated     cortical     parenchyma     and     occasionally 
sclerenchyma.     Notice  the  pits.     Draw. 

9.  The  bundle,  sheath  ;  cells  elongated,  rather  difficult  to 
distinguish.     Draw. 

10.    The  fibro-vascular  bundle.     Study 


182  FIELD  OATS. 

a.  The  pitted  fibrous  cells,  tracheidesy  which  constitute 
most  of  the  bundle. 

b.  The  one  or  two  pitted  vessels. 

c.  Draw,  showing  both  vessels  and  tracheides. 
Mount  about  one  centimeter   of   the  tip  of   a  root  from 

plants  that  have  been  grown  upon  blotting  paper.     Exam- 
ine with  a  low  power,  and  note 

11.  The  root-hairs.     Observe  their  relative  length. 

12.  The  root-cap ;    the  outer  cells  sloughing  off.     Draw. 
Study  the  root-hairs  with  a  high  power.     Notice 

13.  The  shape,  mode  of  attachment  and  contents.     Draw. 
Cut  a  median  longitudinal  section  of  the  tip  of  a  root, 

including  the  root-cap.7     Treat  with  potash,  examine  with 
a  high  power,  and  note 

14.  The  blunt,  or  even  notched  tip  of  the  root  proper. 

15.  The  sharp  conical  root-cap.      Note  the  shape  of  the 
cells  near  the  root-tip,  and  the  changed  shape  near  the 
periphery. 

1 6.  The  growing  point,  a  cluster  of  small  cells,  just  back  of 
the  root-cap,  in  the  middle  of  the  root-tip. 

17.  A  short  distance  behind  the  tip  of  the  root,  the  slight 
differentiation  of  the  tissues  into  three  regions  : 

a.      A  central  one,  the  plerome. 

/;.      An  outer  one,  consisting  of  a  single  row  of  cells, 

the  dermatogen. 

Between  the  plerome  and  dermatogen,  the  periblem. 

Trace  these  three  regions  down  to  the  growing 

point,  and  notice  their  relations  there. 

7  This  is  very  difficult  to  do  if  fresh  roots  are  used,  but  easier  by  using 
roots  that  have  been  kept  for  a  few  hours  in  alcohol.  The  student  should 
cut  a  series  of  sections  through  the  whole  root.  The  median  one  can  then 
be  selected. 


A  VEX  A  SATir.l.  183 

e.  Trace  them  backward  ;  notice  that  the  plerome 
becomes  the  fibro-vascular  bundle  ;  the  periblem, 
the  cortical  parenchyma  ;  the  dermatogen,  the 
epidermis. 

Cut  a  transverse  section  of  the  oldest  part  of  a  root  which 
has  grown  on  blotting  paper.  Examine  with  a  high  power. 
Compare  with  the  section  of  the  large  lateral  roots,  already 
studied.  Notice 

1 8.  The  origin  of  the  root-hairs. 

19.  The  differences  in  the  fibro-vascular  bundle,  particularly 
the  presence  of  a  large  axial  vessel. 

r>.  THE  STEM.  Cut  a  transverse  section  from  one  of  the 
younger  parts  of  the  stem,  e.  §-.,  between  the  flower  cluster 
and  the  first  leaf.  Examine  with  a  low  power,  and  note 

1.  An  outer  cortical  part,  of  varying  thickness,  composed 
of  small  dense-looking  cells,  the  epidermis  and  hypo- 
derma. 

2.  In  the  cortex  lighter  spots,  in  pairs,  at  almost  regular 
i ntervals,  chloropJn 'll-bcaring  parenchyma. 

3.  An  inner  part,  consisting  of  large  empty  parenchyma 
cells,  the  fundamental  parenchyma,  with  fibro-vascular 
bundles  at  regular  intervals. 

Examine  with  a  high  power.     Study 

4.  The  epidermis.      Note  the    thick  walls,   showing    two 
layers,  and  the  cuticle.     Draw. 

a.  Observe  in  some  sections  a  pair  of  smaller,  peculiar 
cells  in  the  epidermis  over  an  intercellular  space 
in  the  chlorophyll-bearing  parenchyma,  the  guard 
cells  of  a  stoma.  The  two  adjacent  epidermal  cells 
are  also  modified  somewhat.  Draw. 

5.  The    hypoderma.     Note    the  thick  walls  of   the   cells 


184  FIELD  OATS. 

which  increase  in  size  toward  the  parenchyma,  but  do 
not  merge  into  it.     Draw. 

6.  The  chlorofhyll-bearing parenchyma.     Note 

a.  The  shape,  size  and  arrangement  of  the  cells. 

b.  The  thin  walls. 

c.  The    contents  ;  protoplasm  and  chlorophyll  bodies 
which  are  green,  if  fresh  stems  are  used.     Notice 
the  position  of  the  chlorophyll  bodies.8 

d.  Draw  a  few  cells. 

7.  The  fundamental  parenchyma.     Note  the  size  and  shape 
of  the   cells,    and   the  triangular  intercellular   spaces. 
Draw  a  few  cells. 

8.  The  fibro-vascular  bundles.     Notice  the  two  series  of 
bundles  :  the  larger  ones  nearer  the  central  cavity  of 
the  stem  ;  the  smaller  between  the  paired  groups  of 
chlorophyll-bearing   parenchyma.      In  the  larger   ob- 
serve 

a.  The  external  sheath,   an  irregular   layer  of  cells, 
with   slightly  thickened  walls,9    surrounding    the 
bundle,  and  thicker  on  its  peripheral  side.  Exam- 
ine it  in  a  section  from  an  older  part  of  the  stem  ; 
note  the  thickness  of  the  walls. 

b.  The  tracheary  tissue;  on  the  right  and  left  of  the 
bundle  two  large  pitted  vessels  ;    toward  the  axial 
side    one   or  two   annular  vessels  j    between    the 
large  pitted  vessels  a  transverse  band  of  smaller 
pitted  vessels.10 

c.  Between    the    annular   vessels   and  the   external 


8  They  may  be  made  plainer  by  staining  with  magenta. 

9  If  it  can  not  be  discerned,  stain   slightly  with  magenta  ;  these   cells 
take  a  deeper  red  than  the  rest. 

10  Stained  a  deeper  red  in  the  magenta-treated  section. 


A  VENA  SATIVA.  185 

sheath  sometimes    an  intercellular  cavity   formed 
by  breaking  in  growth. 
d.      Toward  the  peripheral  side  of  the  bundle  a  group 

of  thin- walled  conducting  cells." 
c.      Draw  the  bundle. 
/.      Compare  the  structure  of  the  smaller  bundles  with 

the  foregoing,  noting  differences. 

Cut  a  number  of  longitudinal  sections  of  the  stem,  and 
examine  with  a  high  power.     Study 

9.    The  epidermis.     Note 

a.  The  thickened  outer  wall  ;  elongated  shape;  chan- 
nel pits. 

b.  The  alternately  long    and   short    cells    in   some 
sections. 

c.  Draw. 

Some  of  the  sections  will  be  likely  to  pass   through   a 
stoma.     Examine 

d.  The  guard  cells  ;  note  the  enlarged  ends  and  nar- 
row body.     Draw. 

10.  The    hypoderma  ;    note    the   extreme   elongation   and 
tapering  ends  of  the  cells.     Draw. 

11.  The  chlorophyll-bearing  cells  ;  note  their  shape,  arrange- 
ment and  contents.     Draw. 

12.  The   futidamental  parenchyma;    note     the    size    and 
shape  of  the  cells,  and  the  thin  places  in  the  walls. 
Draw  a  few  cells. 

13.  The  fibro-vasciilar  bundles  ;   note  in  the  various  sec- 
tions ia 

a.      The  slightly  thickened,  sparsely  pitted,  elongated 


11  Unstained  with  magenta. 

'-'  No  one  section  can  be  found  to  show  all  points. 


1 86  FIELD  OATS. 

cells  of  the  external  sheath  having  slightly  oblique 
end  walls. 

b.  The  delicate  walls  and  elongation  of  the  conduct- 
ing cells. 

c.  The  pitted  vessels,  large  and  small. 

d.  The  annular  vessels.      Notice  the  various  positions 
of    the  rings.     Study   their  cut  ends   where  the 
razor  has  passed  along  a  vessel. 

e.  Draw  a  few  cells  of  each  tissue. 

Cut  a  thin  slice  from   the   surface   of   a   stem,   examine 
with  a  high  power,  and  note 

14.    The  epidermis. 

a.  The  cells  above  the  hypoderma  ;  shape  and  ar- 
rangement. 

b.  The  cells  above  the  chlorophyll  tissue,   including 
the  stoma  ;  shape  and  arrangement. 

c.  The  numerous  pits  in  the  surface  wall,  and  in  the 
side  walls  beneath. 

d.  Draw. 

C.  THE  LEAF.     Cut  a  transverse  section,  and  examine 
with  a  high  power.     Study 

i.    The  epidermis.     Notice 

a.  Its  cuticularized  outer  wall  with  minutely  uneven 
free  surface. 

b.  Ite  guard  cells.   Note 

i.  The  different  appearance  of  these  cells, 
according  as  the  section  has  passed  through 
the  bodies  or  ends. 

ii.  The  small  size  and  thick  walls  of  the  body, 
the  larger  size  and  thinner  walls  of  the  ends. 

c.  The  modified  epidermal  cells  adjoining  the  guard 
cells. 


A  VEX  A  SATIVA.  187 

d.  Draw  various  sections  of  stomata,  with  adjoining 
cells  of  the  epidermis. 

e.  The  modified  large  epidermal  cells  in  the  depres- 
sions on  the  upper  surface,  the  hygroscopic  cells. 
Draw. 

/.      The  modified  epidermal  cells  at  the  summit  of  each 
ridge;  sometimes  teeth  may  be  seen.     Draw. 

2.  The  hypoderma.     Note  its  position  and  the  character 
of  the  cells. 

3.  The  mesophyll,  all  the  chlorophyll-bearing  part  of  the 
leaf.     Note 

a.  The  slight  elongation  of  those  cells  next  the  epi- 
dermis, forming  palisade  parenchyma. 

b.  The  large  intercellular  space  under  each  stoma,  and 
the  numerous  smaller  ones  in  other  places. 

c.  The  abundant  chlorophyll  bodies. 

4.  The  fundamental  tissue ;  often  reduced  to  only   one 
row  of  large  empty  cells  surrounding  the  bundles. 

5.  ^\^  fibro-vascular  bundles  ;  compare  those  forming  the 
midrib  and  main  veins  of  the  leaf  with  those  studied  in 
the  stem.     Compare  with   these   the   bundles  of   the 
smaller    veins,   noting  what  tissues    are  absent  from 
them. 

6.  Draw  a  portion  of  the  section,  including  a  large  fibro- 
vascular  bundle,  and  some  cells  of  the  mesophyll  and 
fundamental  tissue. 

7.  Make  a  diagram  of  the  leaf  section  to  show  relative 
position  and  size  of  the  different  parts. 

Strip  off  two  pieces  of  the  epidermis.  Mount  one  piece 
with  the  outer  surface  uppermost,  and  the  other  with  the 
inner  surface  uppermost.  Note 


1 88  FIELD  OATS. 

8.  The  epidermal  cells. 

a.  The  shape  of  those  lying  above  a  vein,   together 
with  the  short  strong  trichomes,  each   bearing  a 
very  sharp  point,  directed  forward. 

b.  The  shape  of  those  lying  among  the  stomata. 

c.  The  stomata.     Note 

i.     The  regular  arrangement  in  double  or  triple 

rows, 
ii.     The  pair  of   narrow   epidermal   cells,  which 

stand  one  on  each  side  of  the  guard  cells, 
iii.    The  shape  of  the  guard  cells  ;  the  thick  walls 

of  the  body  and  thin  walls  of  the  ends, 
iv.     Draw,  showing  the  several  sorts  of  epidermal 

cells. 

9.  The  shape  and  contents  of  the  mesophyll  cells,  some  of 
which  will  almost  invariably  adhere  to  the  epidermis 
when  stripped  off.     Draw. 

10.  Make  a  transverse  section  of  the  leaf  sheath,  and  note 
its  intermediate  character  between  that  of  the  stem  and 
of  the  leaf  blade  already  studied.  Draw  sufficient  to 
show  the  various  tissues,  and  their  arrangement. 

D.   THE  FLOWER. 

i.  The  glumes  and  palets.  Make  a  transverse  section 
through  the  upper  part  of  a  spikelet  and  transfer  it  to 
the  slide  without  disarranging  the  parts.  Note 

a.  The  thin-walled  cells  forming  the  inner  portion, 
and  the  thick-walled    cells  forming  the  outer  por- 
tion  of   each    part.     Draw    from    two    or    more 
regions. 

b.  The  angles  of  the  palets,  bearing  stiff  trichomes. 
Draw. 


A  VENA  SATIVA.  189 

2.  The  anthers.     Tear  off  bits  of  the  wall  of  an  empty 
anther.     Mount  one  outside  up  and  the  other  inside  up. 
Focus  on  the  surface  of  the  first,  and  note 

a.  The  epidermis  ;  its  wrinkled  walls  ;  the  shape  of 
its  cells.     Draw. 

Focus  on  the  surface  of  the  second,  and  note 

b.  The   emfotJicciuM,    the   layer  of    cells    lining   the 
anther.     Observe 

i.     The  infolded  thickenings  of  the   side  walls  of 

the  cells. 

ii.     The  shape  of  the  cells, 
iii.     Draw. 

Cut  a  transverse  section  through  the  lower  part  of  a 
spikelet  which  has  not  bloomed,  and  transverse  sections  of 
the  anthers  will  be  obtained.  Notice 

c.  The  large  inflated  epidermal  cells. 

d.  The  very  narrow  endothecial  cells,  with  the  thick- 
enings of  the  walls  extending  the  full  height,  mak- 
ing it  difficult  to  distinguish  their  outline. 

e.  Draw  a  few  of  the  two  kinds  of  cells. 
Under  low  power,  notice 

/.      The  two  lobes  of  the  anther,  theca. 

g.      The  connective  which  joins  them,  containing  a  fibro- 

vascular  bundle. 
//.      The  four  cavities,  appearing  like  two  after  dehis- 

cence.      Usually  the   manner  of   dehiscence   can 

be  detected. 

Using  the  same  section,  under  high  power,  notice 

3.  The  pollen. 

a.  The  shape  of  the  cells. 

b.  The  small  globular  protuberance  sometimes  seen 
when  the  spore  lies  properly. 


1 90  FIELD  OATS. 

c.  The  optical  section  of  the  wall ;  its  continuity  inter- 
rupted at  the  protuberance. 

d.  The  contents.      Burst    some     spores  by   pressing 
lightly  on  the  cover-glass  with  a  needle.     Note 

i.  Here  and  there  entirely  empty  bursted  sacs, 
the  extine.  Notice  the  minute  roughening 
of  the  surface  ;  the  thin  spot  or  opening, 
through  which  in  some  cases  when  unburst  the 
intine  protrudes. 

ii.  The  contents  of  some  spores  surrounded  by  the 
intine  t  escaped  from  the  extine  and  become 
much  larger.  In  some  cases  the  protuberance 
may  still  be  seen. 

iii.  The  contents  of  other  spores  free  in  the  water 
of  the  slide,  showing  innumerable  fine  gran- 
ules. Note  their  shape,  and  treat  with  iodine 
to  determine  their  nature. 

e.  Draw  an  uninjured  spore,  showing  its  structure. 

4.  The  styles  and  stigmas.  Cut  off  one  of  the  styles  near 
its  attachment.  Mount  and  examine  with  a  low 
power.  Note 

a.  The  tapering  style  with 

b.  Numerous    undivided     branches,    the     stigmas, 
roughened  with  innumerable  points. 

c.  The  grains  adhering  to  the  stigmas. 
Examine  with  a  high  power.     Observe 

d.  The  thin-walled  nucleated  cells,  forming  the  stig- 
mas ;  the  proximal  ends  are  overlapped  by  other 
cells. 

e.  The   adherent  grains.     Notice  that  some   of  the 
spores  have   emitted  through  the  perforation   in 
the  extine  a  slender   tube   which    penetrates  the 
stigma.     Notice  that  the   granules  of  the  pollen 


A  VENA  SATIVA.  191 

spore  also  enter  this   tube.      Observe  that   some 
spores  have  become  empty. 

f.      Draw,    showing    structure    of    stigmas   and   the 
entrance  of  a  pollen  tube. 

5.  The  trichomes  of  the  wary.  Cut  off,  mount,  and 
examine  with  a  high  power  some  of  the  trichomes  which 
clothe  the  apical  portion  of  the  ovary.  Note  shape  and 
contents.  Draw. 

E.  THE  FRUIT.  Remove  the  chaff  from  a  grain,  and 
cut  a  transvense  section  near  the  middle,  having  previously 
soaked  it  in  warm  (not  hot)  water  for  a  few  minutes.13 
Note 

1.  While  mounting,  the  abundant  whitish  powder  which 
escapes  into  the  water,  clouding  it  more  or  less. 

Examine  with  a  high  power  and  note 

2.  The  outermost  coat  of  the  fruit,  the  ovary  wall,  some- 
times splitting  into  two  layers  ;  the  cells  can   only  be 
made  out  with  great  difficulty. 

3.  The  layer  of  large  cells,  containing  granular   proteid 
matters,  chiefly  gluten.     Note  shape,  and  test  contents 
with  iodine.     Draw. 

4.  The  large  cells  packed  with  granules  of  starch,  made 
blue  by  the  iodine.     The  outline  of  these  cells  is  best 
seen  when  the  starch  has  escaped  from  them. 

5.  The  tip  of  the  embryo  will  usually  appear  at  one  side  of 
the  section. 

Cut  a  median  longitudinal  section  through  the  groove  of 
a  soaked  fruit.  Treat  with  potash  to  clear  up  the  embryo, 
and  examine  with  a  low  power.  Note 

13  An  immersion  of  an  hour  or  longer  in  cold  water  will  answer  the 
same  purpose. 


*92  FIELD  OATS. 

6.  The  three  parts  of  the  fruit  :  the  walls   of  the  ovary 
and  gluten-containing  cells  ;  the  starchy  part  of  the 
grain  ;  the  embryo. 

Study  the  embryo  /  note 

7.  The  long  leaf,  scutellum,  next  the  starch. 

8.  The  bud,  plumule,  near   the   base    of  the   scutellum, 
showing  one  or  two  leaves. 

9.  The  root  near  the  base  of  the  embryo,  with  its  root-cap, 
and  enveloped  by 

10.  The  root-sheath  ;  notice  that  it  is  continuous  with 

11.  The  short   stem,  caulicle,   to  which   the   scutellum   is 
attached,  bearing  the  plumule  at  its  upper  and  the  root 
at  its  lower  end. 

Examine  with  high  power.     Note 

12.  The  tissues  of  the  fruit,  essentially  as  in  the  trans- 
verse section. 

13.  The  tissue  of  the  embryo  ;    parenchyma  with   much 
protoplasm. 

ANNOTATIONS. 

The  division  of  the  slender,  slowly  tapering  stem  of 
Avena  into  ring-like  nodes  and  elongated  internodes 
shows  these  features  distinctly  marked  for  the  first 
time.  The  disposition  of  the  material  in  the  form  of 
a  hollow  cylinder  gives  greater  rigidity  than  would 
the  same  amount  of  material  in  a  solid  stem. 

At  some  of  the  lower  nodes  of  the  stem  the  endog- 
enous formation  14  of  roots  can  be  well  seen,  as  young 

14  Cf.  Prantl  and  Vines,  Text-book,  p.  22. 


AVENA  SATJVA.  193 

roots  can  be  frequently  found  just  breaking  through 
the  superficial  tissues. 

The  leaves  of  oats  are  sharply  distinguished  into  a 
sheathing  base  and  a  spreading  blade.  The  membra- 
nous outgrowth,  the  ligule,"  which  is  found  at  their 
junction,  is  common  in  leaves  of  this  character. 

The  flower  of  oats,  like  that  of  the  pine,  is  a  meta- 
morphosed shoot,  in  which  the  axis  is  the  stem,  and 
the  lateral  organs  which  it  bears,  leaves.  At  the  base 
of  each  spikelet  are  to  be  found  two  glumes  or  bracts, 
which  thus  subtend  and  more  or  less  completely  inclose 
the  whole  cluster.  At  the  base  of  each  flower  is  a 
single  bract,  the  flowering  glume,  having  the  flower  in 
its  axil.  Concerning  the  homology  of  the  palet  and 
lodicules  much  discussion  has  arisen.  Payer  1<s  asserts 
that  the  palet  is  a  double  organ  and  that  the  two  keels 
on  the  palet  are  primitively  distinct.  Schacht  17  sees 
in  the  palet  two  parts  of  a  trimerous  whorl,  of  which 
the  anterior  part  is  suppressed.  Roper,  Wigand, 
Nageli  and  others  conclude  from  comparative  and 
developmental  researches  that  the  palet  is  primitively 
single  and  takes  on  its  two-keeled  condition  subse- 
quently.18 Hackel 19  believes  "  that  the  palea  and  the 
pair  of  lodicules  (when  two  only)  are  each  single,  more 
or  less  bifid  organs,  and  that  they  and  the  third  lodi- 
cule,  when  present,  must  be  regarded  as  two  or  three 

15  For  a  statement  of  its  homology  see  Gray,  Struct.  Botany,  pp.  106, 
211. 

16  Organogenic  de  la  fleur,  p.  701. 
11  Das  Mikroskop,  2  Aufl.,  p.  170. 

18  Cf.   Eichler,   Bluthendiagramme,  p.  120. 

19  Untersuchungen  liber  die  Lodiculae  der  Graser,  Engler's  Bot.  Jahr- 
biicher,  i,  p.  336. 


194  FIELD  OATS. 

bracteoles  inserted  fore  and  aft  on  the  floral  axis  below 
the  flower,  and  he  has  made  out  a  good  case  in  favor 
of  his  view  but  perhaps  not  an  unanswerable  one."  20 
Bentham  "  adds  :  "  The  search  for  homologies  to  the 
palea  and  lodicules  in  the  orders  nearly  allied  to  the 
Graminece  has  met  with  but  little  success  ;  "  and  again, 
"  The  palea  and  lodicules  of  Graminece  may  represent 
perianth  segments  of  an  outer  and  inner  series,  though 
I  by  no  means  pretend  to  assert  it  as  a  proved  fact." 
Again,"  "  In  all  cases,  the  palea,  whatever  its  origin, 
is  called  upon  in  conjunction  with  the  subtending 
glume  to  perform  more  or  less  of  the  functions  of  the 
deficient  or  absent  perianth." 

It  is  to  be  noticed  that  the  male  and  female  repro- 
ductive organs  occur  in  the  same  flower,  which  is 
therefore  hermaphrodite.  The  stamens  of  oats  are 
to  be  looked  upon  as  metamorphosed  leaves,  as  in  the 
pine ;  it  seems  probable,  though  not  definitely  proved, 
that  the  pollen  sacs  are  homologous  with  those  of  the 
pine.  The  immature  pollen  spore  is  two-celled,  as  in 
most  other  angiosperms,23  and  it  is  doubtful  whether 
there  is  any  trace  of  a  prothallium.  This  stage  in  the 
life  cycle  of  the  plant,  which  is  so  marked  in  the  moss 
and  liverwort,  far  less  prominent  in  the  fern,  reduced, 
if  it  can  be  considered  present  at  all,  to  but  a  cell  or 
two  in  the  pine,  is  in  this  plant  probably  entirely  sup- 
pressed. 

Attention  is  called  to  the  fact  that  the  ovule  is  not 

20  Bentham,  Notes  on  Gramineae,  Jour.  Linn.  Soc.,  xix,  p.  23. 

21  L.  c.,  p.  24. 

'2  L.   C.,p.  25. 

23  Cf.  Strasburger,  Neue  Untersuchungen,  p.  5, 


A  VENA  SATIVA.  1 95 

naked  as  in  pine,  but  that  it  is  surrounded  by  an  organ 
peculiar  to  angiosperms,  the  ovary,  which  in  this  plant 
adheres  to  the  surface  of  the  ovule.  It  is  much  better 
developed  in  Trillium  and  Capsella,  to  which  for  its 
study  the  student  is  referred.  Since  the  ovule  is  thus 
inclosed,  stigmas  have  been  developed  as  naked  pollen- 
catching  surfaces,  to  which  the  pollen  spores  can 
adhere,  and  through  whose  loose  tissues  they  can  eas- 
ily send  their  tubes. 

The  adherence  of  the  ovary  wall  to  the  ripened  seed 
gives  rise  to  a  fruit  peculiar  to  grasses,  the  grain,  which 
is  commonly  mistaken  for  a  simple  seed. 

The  fibre-vascular  system  is  well  developed  in  oats, 
and  is  of  the  typical  monocotyledonous  form.  The 
hypodermal  fibers  of  both  stem  and  leaves  give  addi- 
tional strength  to  these  organs.  The  bundles  through- 
out the  stem  are  of  the  collateral  type,  as  in  the  pine, 
but  with  this  difference ;  whereas  in  the  pine  there 
remains  a  cambium  layer  between  the  xylem  and 
phloem,  here  there  is  no  cambium.  The  continued 
growth  of  the  bundle  is  therefore  impossible,  whence 
it  is  known  as  a  closed  bundle.  The  axial  bundle  of  the 
root  is,  like  that  of  the  fern,  a  radial  one.  In  the  fern 
root  a  single  apical  cell  forms  the  growing  point  of 
the  root ;  in  oats  the  apical  cell  is  replaced  by  a  clus- 
ter of  cells.  The  remark  respecting  the  root-epidermis 
of  Adiantum  "  is  equally  applicable  here  concerning  the 
older  roots. 

In  the  leaves  the  most  novel  structure  is  the  groups 
of  hygroscopic,  or  as  they  were  first  named  by  Duval- 

24  Cf.  also  Goodale,  Physiological  Botany,  p.  108. 


196  FIELD  OATS. 

Jouve,"  bulliform  cells.  They  are  found  in  all  grasses 
that  roll  and  unroll  their  leaves.  These  cells  when 
they  lose  part  of  their  moisture  contract  and  roll  up 
the  leaf,  which  again  expands  upon  their  regaining  it. 
This  movement  reduces  the  amount  of  surface  available 
for  evaporation,  and  is  a  safeguard  for  the  plant.  It 
will  be  remembered  that  the  moss  leaf  accomplishes 
the  same  result,  but  without  a  specialized  apparatus. 

t5  Etude  anatomique  de  quelques  Graminees,  1870,  p.  320. 


TRILLIUM. 

Trillium  rccurvatum  Beck. 

PRELIMINARY. 

THE  Trillium  designated,  as  well  as  T.  sessile,  is 
found  in  the  spring,  generally  in  rich  woods,  and  may 
be  readily  recognized  by  the  naked  stems,  from  fifteen 
to  thirty  centimeters  (six  inches  to  a  foot)  or  more  high, 
bearing  at  the  summit  a  circle  of  three  broad  netted- 
veined  leaves,  at  the  center  of  which  (the  apex  of  the 
stem)  stands  a  single  sessile  dark-purple  flower.  The 
stem  rises  from  a  deep-seated,  somewhat  toothed,  very 
thick  rootstock,  which  bears  the  fibrous  roots 
along  its  under  surface.  In  the  other  Trilliums,  which 
are  at  all  common,  the  flowers  are  usually  white 
or  pinkish,  or  purple  in  one  case,  and  stalked.  Any 
species  may  be  used  for  the  laboratory  work. 

Although  Trillium  is  now  considered  a  member  of 
the  lily  family,  the  largest  order  of  petaloideous  mon- 
ocotyledons, it  is  not  a  very  characteristic  member, 
but  has  been  selected  for  its  general  distribution,  its 
completeness  and  simplicity,  and  for  its  convenient 
size. 

The  materials  needed   are  fresh  or  alcoholic  spec- 


198  TRILLIUM. 

imens    of    roots,     rootstocks,    stems,    leaves,    flowers 
and  fruit ;  potassic  hydrate ;  magenta  ;  and  iodine. 


LABORATORY  WORK. 

GROSS  ANATOMY. 

A.  GENERAL  CHARACTERS.     Note 

1.  The  main  axis,  consisting  of  a  thickened,  horizontal, 
under-ground  stem,  the  rootstock,  and  a  single  vertical 
branch,  the  aerial  stem,  bearing  a  terminal  flower. 

2.  The  rootstock,  bearing  as  lateral  appendages  the  roots, 
and  modified  leaves  in  the  form  of  broad  membranous 
scales. 

3.  The  aerial  stem,  bearing  as  lateral  appendages  a  whorl 
of  three  leaves,  and  the  parts  of  the  flower. 

B.  THE  ROOTS.     Note 

1.  Their  arrangement  on  the  rootstock. 

2.  The  almost  entire  absence  of  branching. 

3.  The  surface,  especially  the  transverse  wrinkles  on  older 
parts. 

4.  The  root-hairs. 

Mount  a  transverse  section  of  the  proximal  portion  of  a 
large  root,  and  notice 

5.  The  presence  and  relative  areas  of  three  regions: 
a.      The  cortical  region  of  two  layers  : 

i.     An  outer  layer  of  small  cells. 
ii.     An  inner  layer  of  large,  irregular,  loose  cells, 
often  torn  through  in  sectioning,  the  unequal 


TRILLIUM  RECURVA  TUM.  199 

development    of    which    gives    rise    to    the 
wrinkling. 

b.  The  median  large-celled  or  parenchyma  region. 

c.  The  central  or  fibro-vascular  region,  in  which  may 
be  detected  the  large   openings  of    four  or  five 
tracheary  vessels. 

Mount  a  longitudinal  section  through  the  center  of  the 
root  and  notice 

6.  The  several  regions  as  before. 

7.  The  depth  of  the  surface  wrinkles. 

8.  Diagram  both  the  transverse  and  longitudinal  sections. 

C.    THE  ROOTSTOCK  (Subterranean  Stem).     Note 

1.  The  shape  and   thickness. 

2.  The  succession  of  nodes   and  inter  nodes. 

a.  The  number  in  an  unbroken  rootstock. 

b.  The   scars   of  former  branches,  and  the  varying 
number  of  intervening  nodes. 

c.  The  irregular  growth  of  the  internodes. 

3.  The  prevailing  number  of  roots  from  each  node. 
Mount  a  transverse  section  ;  notice 

4.  1\&  three  parts  : 

a.  The    extremely  narrow  brownish   cortical  region, 
forming  the  boundary  of  the  section. 

b.  The  great  mass  of  the  stem,  whitened  with  the 
reserve   food   material.     In  thin  parts  of  the  sec- 
tion, where  the  food  material  has  been  washed  out 
in  mounting,  note 

i.      The  delicate  colorless  tissue,  fundamental  par- 
enchyma. 


200  TRILLIUM. 

Tease  a  bit  of  the  stem  in  a  drop  of  water  on  another 
slide,  treat  with  iodine,  and  note 

ii.      The  color  imparted  to  the  food  material,  indi- 
cating its  nature. 

c.      Scattered    irregularly    through    the    section    the 
comparatively   few   small   dark   areas,  the    fibro- 
vascular  bundles. 
Make  a  longitudinal  section,  and  notice 

5.  The  three  parts  seen  in  the  transverse  section  ;  the 
bundles  branching  irregularly  and  obscurely. 

6.  The  growing  apex.     Note 

a.  The  shape. 

b.  The  sheathing  membranous  scales. 

c.  The  position  of  the  aerial  branch. 
Bisect  the  apex,  and  upon  the  cut  surface  notice 

d.  The  two  or  more  rather  thick  projecting  bracts. 

e.  Beneath  these  a  very  small  protuberance,  the  grow- 
ing point  of  the  stem,  sometimes  accompanied  by 
smaller    lateral    protuberances,   the    rudimentary 
scales. 

/.      Draw  the  bisected  apex. 

D.  THE  BRANCH  (Aerial  Stem).     Note 

1.  The  absence  of  nodes  below  the  whorl  of  leaves. 

2.  The  smoothness  of  the  surface. 
Mount  a  transverse  section.     Notice 

3.  Ite  three  parts  : 

a.  The  very  narrow  cortical  region. 

b.  'Yhe  fundamental  parenchyma,  forming  the  ground 
work  of  the  section  ;   the  cells  appearing  empty. 

c.  The  limited  number  of  fibre-vascular  bundles;  note 

i.     Their  arrangement  and  relative  size, 


TRILLIUM  RECUR  VA  TUM.  201 

ii.  The  two  areas  in  each  :  the  light  colored  por- 
tion lying  toward  the  outside  of  the  stem,  the 
phloem,  the  shaded  portion  lying  toward  the 
center  of  the  stem,  the  xylcm. 

4.  Draw  the  section. 

5.  Make  a  longitudinal  section  and  note  the  several  parts 
seen  in  the  transverse  section.     Draw. 

E.  THE  LEAF.     Note 

1.  The  scale  leaves  of  the  rootstock. 

a.  The  bases  of  decayed  scales  at  each  node. 

b.  Younger  ones,  sheathing  the  apex  of  the  rootstock 
and  base  of  the  aerial  branch. 

Mount  a  portion  of  a  scale  and  notice 

c.  The  parallel  veins,  and  intervening  parenchyma. 

d.  Numerous  dark  spots,  clusters  of  raphides. 

2.  The  foliage  leaves  of  the  aerial  stem. 

a.  The  number  and  arrangement. 

b.  The  shape. 

c.  The  particular   outline  of  the  apex,  and  of   the 
base. 

d.  The  short  stalk,  petiole,  if  present. 

e.  The  distribution  of  the  reins. 

Mount  a  transverse  section  from  near  the  base  of  the  leaf, 
and  note 

/.      The  several  parts  : 

The  colorless  epidermis. 

The  reins,  the  largest  projecting  on  the  lower 
side  ;  each  containing 

iii.  A  fibro-vascular  bundle,  having  the  phloem 
area  toward  the  under  side  of  the  leaf  ;  accom- 
panied in  the  largest  veins  by 


202  TRILLIUM. 

iv.    Colorless  parenchyma. 

v.     The  darkened  (in  fresh  specimens  green)  mes- 

ophyll. 

Mount  a  portion  of  the  epidermis  stripped  from  the  upper 
surface  of  the  leaf,  and  beside  it  a  portion  from  the  under 
surface.  Note 

g.      The  numerous  dots  in  that  from  the  lower  surface, 

the  stomata. 

h.     The  absence  of  stomata  in  that  from  the   upper 
surface. 

F.  THE  FLOWER.     Note 

1.  The  several  parts  arranged  in  whorls. 

a.  The  outer  whorl  of  three  sepals,  constituting  the 
calyx. 

b.  The  second  whorl  of  three  petals,  constituting  the 
corolla. 

c.  The  third  and  fourth  whorls  of  three  stamens  each, 
constituting  the  androecium, 

d.  The  innermost  whorl  of  three  partly  united  carpels, 
constituting  the  gynoscium. 

2.  That  the  parts  of  the  flower  arise  from  the  broadened 
extremity  of  the  stem,  the  receptacle. 

3.  The  alternation  of  the  parts  of  each  whorl  with  those  of 
the  whorl  next  to  it. 

4.  The  sepals. 

a.  The  shape. 

b.  The  color  in  a  fresh  specimen. 

c.  The  venation. 

d.  Draw  a  single  sepal. 

5.  The  petals. 


TRILLIUM  RECUR  VA  TUM.  203 

a.  The  shape. 

b.  The  color  in  a  fresh  specimen. 

c.  The  venation. 

d.  Draw  a  single  petal. 

6.  The  stamens. 

a.  The  several  parts  of  each. 

The  stalk  or  filament,  passing  into 
The  connective,  on  the  right  and  left  margins 
of  which  are  borne 

iii.  The  pollen  sacs,  or  thecce  ;  the  connective  and 
thecae  together  constituting  the  anther. 

b.  Draw  a  stamen. 

Mount  a  transverse  section  of  the   filament,  along  with 
one  of  the  anther,  and  note 

c.  The  filament. 

\.     The  outline. 

ii.     The  uniform  ground  tissue,  containing  a  cen- 
tral fibrO'Vascular  bundle. 
iii.     Draw. 

d.  The  anther. 

i.  The  outline  of  the  connective,  and  character  of 
its  tissues. 

ii.  The  form  of  the  thecce.  The  mode  of  burst- 
ing is  often  well  shown. 

iii.     Draw  the  section 

e.  The  pollen,  escaped  from  the  thecae  and  appearing 
as  fine  particles.     Dust  some  from  an  anther  and 
examine  dry,  noting  color  and  pulverulence. 

7.  The  carpels. 

a.      The  part's  of  each. 

i.  The  enlarged  basal  portion,  bearing  a  pair  of 
prominent  ridges,  united  with  the  bases  of  the 
other  carpels  to  form  the  compound  ovary. 


TRILLIUM. 

ii.     The  tapering  divergent  styles. 
iii.     The  double  wavy  crest  along  the  inner  face  of 
each  style,  the  stigma. 

b.  Draw  the  three  carpels. 

Make  a  transverse  section  through  the  middle  of  the 
style  ;  mount,  and  notice 

c.  The  outline,  including  the  stigma. 

d.  The  central  fibro-vascular  bundle. 

e.  The  stigma. 

i.     The  recurved  sides,  and  deep  median  groove 

extending  in  to  the  central  bundle, 
ii.     The  velvety  papilla  clothing  its  surface. 
/.      Draw  the  section. 

Mount  several  transverse  sections  of  varying  thickness 
passing  through  the  middle  of  the  compound  ovary,  and 
notice 

g.  The  three  similar  parts  belonging  to  the  three  car- 
pels of  which  it  is  composed,  each  consisting 
of 

i.     The  two  prominent  ridges  or  wings. 
ii.     The  fibro-vascular  bundle  lying  in  the  tissue 

between  the  ridges. 

iii.     The  sides  of  the  carpel  uniting  with  the  sides 

of  the  adjoining  carpels,  extending  into  the 

cavity  of  the  ovary  and  meeting  in  the  center, 

forming  the  three  placentae. 

iv.     The  two  or  more  fibro-vascular  bundles  of  the 

placenta. 

v.     The  rounded  ovules  in  the  cavity  of  each  car- 
pel, borne  on  the  sides  of  the  right  and   left 
placentae. 
h.      Draw  the  section. 

G.  THE  FRUIT.     Notice 


TRILLIUM  RECUR  VA  TUM.  205 

1.  The  sepals  still  in  growing  condition. 

2.  The  withered  but  persistent  petals^  stamens  and  styles. 

3.  The  fleshy  winged  pod,    like    the  young  ovary,  but 
larger,  inclosing 

4.  The  seeds.     Note 

a.  The  slender  attachment. 

b.  The  fleshy  body  on  the  side  of  the  seed,  the  stro- 
phiole,  which  is  an  outgrowth  of  the  lower  part  of 

c.  The  stalk  of  the  seed,  funiculus,  extending  beyond 
the  strophiole  as  a  ridge  on  the  seed,  the  rhaphe, 
and  terminating  at 

d.  The  base  of  the  seed,  the  chalaza. 

e.  The  shape. 

/.      The  minutely  granular  surface. 
g.      Draw  a  seed. 

Beginning  at  the  chalaza,  cut  several  very  thin  trans- 
verse sections,  then  another  transverse  section  from  the 
middle  of  the  seed,  mount,  and  notice 

//.      The  thin  brown  coat  of  the  seed,  testa, 
i.       The  uniform  tissue  within,  the  cells  of  which  are 
filled    with    reserve    food    material,    and   in  the 
section  from  the  middle  of  the  seed  are  seen  to 
radiate   from  the  center  to  the  outside. 
j.       In  the   sections  from  the  base  of  the  seed,  the 
small    round   spot,    between    the    center    of  the 
section  and  the  side  next  the  rhaphe,  the  embryo. 

MINUTE  ANATOMY. 

A.     THE     ROOT.     In    a    central    longitudinal    section 
through  the  root-tip,  note  under  low  power 
i.    The  outer  looser  cells  and   inner  more  compact  tissue 
forming    the    root-cap.1 

1  It  may  be  difficult  to  get  the  region  complete. 


206  TRILLIUM. 

2.  A  cluster  of  small  angular  cells  in  the  center  of  the 
section  just  behind  the  root-cap,  the  primary  meristem, 
forming  the  growing  point. 

3.  Originating  in  the  primary  meristem,  an  epidermis-like 
row  of  cells  of  the  root  proper,  the  dermatogen,  which 
is  continuous  with  the  epidermis  .of  the  surface  of  the 
root. 

4.  The  central  cylindrical  mass  of  cells,  to  become  the 
fibro-vascular  column,  the  plerome. 

5.  The  region  of  cells  between  the  plerome  and  dermato- 
gen  or  epidermis,  to  become  the  cortical  portion  of  the 
root,  the  periblem. 

6.  The  branching   root-hairs    and   their    relation  to  the 
epidermal  cells. 

7.  Draw  the  section,   showing  the  regions  above  noted. 
Make  a  transverse  section  of  the  root   at  its   wrinkled 

part.     Under  low  power,  notice 

8.  The  peripheral  portion  of  two  or  more  rows  of  rounded 
cells. 

9.  The  underlying  large-celled  tissue,  with  delicate  dis- 
torted walls,  often  torn  in  sectioning. 

10.  The   outer   portion  of  the    core,    with   rounded  cells 
becoming  smaller  as  they  lie  nearer 

11.  The  circular  axial  part  of  the  core,  the  fibre-vascular 
bundle,   containing  several   large  vessels  arranged  in 
four  or  more  short  radiating  rows. 

Use  a  high  power,  and  notice 

12.  The  surface  row  of  cells,  the  epidermis,  slightly  or  not 
at  all  differing  from 

13.  The  cells  beneath  the  epidermis,  the  hypoderma. 


TRILLIUM  RECURTATUM.  207 

14.  The  very  thin  walls  of  the  loose  tissue. 

15.  The  thickened  walls   of   the  outer   part  of   the   core, 
and  the  intercellular  spaces  at  the  angles. 

1 6.  Draw  a  portion  of  these  several  tissues  of  the  root. 

17.  The   somewhat   irregular   row   of   thickened,    slightly 
colored  cells,  the  bundle  sheath,  usually  with  an  evident 
middle  lamella  in  the  walls. 

1 8.  The  fbro-vascular  bundle. 

a.  Immediately  within    the    bundle-sheath   a  row  of 
thin-walled  cells,  the  pericambiitm? 

b.  The  radial  rows  of  large  vessels,  larger  toward  the 
center,  smaller  toward  the  periphery. 

c.  The  intermediate  groups  of  sieve  tissue. 

d.  The  thin-walled  cells  of  the  center  of  the  bundle. 
f.      Draw  the  nbro-vascular  bundle  and  bundle-sheath. 

Make  several  longitudinal   sections  through  the  core  of 
the  root ;  identify  and  study 

19.  The  several  tissues  seen  in  transverse  section,  drawing 
a  few  cells  of  each. 

B.  THE  ROOTSTOCK  (Subterranean  Stem).  Make  a 
transverse  section,  mount  in  strong  potassic  hydrate,  and 
notice 

1.  The  row  of  epidermal  cells  with  brown  outer  walls. 

2.  The  parenchyma  tissue  within,  filled  with   starch,  and 
forming  the  mass  of  the  rootstock. 

3.  Draw  a  few  cells  of  epidermis,  and  of  adjoining  paren- 
chyma. 

4.  The  fibro-vascular  bundles,  cut  at  all  angles,  even  longi- 
8  Sometimes  absent  in  old  roots  by  having  become  permanent  tissue. 


208  TRILLIUM. 

tudinally.  Owing  to  the  difficulty  of  obtaining  good 
sections,  and  the  interference  of  the  starch,  the  further 
study  of  the  bundles  is  deferred  till  they  are  reached  in 
the  aerial  stem. 

Cut  a  thin  slice   from  the  surface  of  the  rootstock,  and 
under  low  power,  notice 

5.  The  shape  of  the  epidermal  cells,  and  absence  of  sto- 
mata.     Draw. 

Make  a  longitudinal  section  through  the  growing  tip   in 
the  plane  of  the  branch,  and  note 

6.  The  sheath  composed  of  one  or  more  sets  of  thickened 
and  partly   coalesced  bracts.     These  bracts  may   be 
detected  in  various  stages  of  growth,   all   originating 
behind 

7.  The  growing  point. 

8.  The  growing  tips  of  rudimentary  roots  and  branches.  Note 
the  exogenous  development  of  a  branch,  all  the  tissues 
of  the  stem  entering  into  it,  and  the  endogenous  devel- 
opment of  a  root,  distinct  from  the  tissues  of  the  stem 
and  pushing  its  way  through  them. 

C.  THE  BRANCH  (Aerial  Stem).    In  a  transverse  section, 
with  a  low  power,  notice 

1.  The  single  row  of  epidermal  cells. 

2.  The  loose,  round-celled  fundamental  parenchyma,  with 
large  intercellular  spaces. 

3.  The  fibro-vascular  bundles,  consisting  of 

a.  The  light  colored  portion,  phloem. 

b.  The  shaded  portion,  xylem. 
Under  high  power  notice 

4.  The  epidermis  and  hypoderma.     Note 


TRILLIUM  RECUR  VA  TUM.  209 

a.  The  thickness  of  the  different  walls. 

b.  Draw. 

5.  ^^ parenchyma  of  the  center  of  the  stem.     Note 

a.  The  shape  of  the  cells. 

b.  The  thinness  of  the  walls. 

c.  The  large  intercellular  spaces, 
if.  Draw. 

6.  'Y\\z  fibro-vascular  bundle.     Note 

a.  rY\\z  phloem,  consisting  of  angular  cells  of  various 
sizes;  the   smaller,  conducting  cells  or  bast  paren- 
chyma, the  larger,  the  sieve  tissue. 

b.  The  xylem,  in  the  smaller  bundles  of  less  area  than 
the  phloem,  but  in  larger  bundles    greater,  and 
spreading  out  on  either  side  the  phloem,  until,  in 
some  cases,  it  entirely  surrounds  it.'     It  is  made 
up  of 

i.     The  vessels  of  various  sizes,  and 

ii.     Interspersed  among  the  vessels  and  extending 

out  on  the  axial  side,  rather  angular  cells,  the 

wood  parenchyma. 

7.  The   absence  of   meristem  cells   between    xylem   and 
phloem,  thus  forming  a  closed  bundle. 

8.  Draw  a  small  and  a  large  bundle. 

Take  a  longitudinal  section  through  the  center  of  the 
stem  and  notice 

9.  The  several  tissues  seen  in  transverse  section. 

a.  The  epidermal   and  hypodermal   tissues.     Draw. 

b.  The  central  parenchyma.     Draw. 

3  Forming  the  external  sheath  (Prantl  and  Vines,  Text-book,  p.  58), 
which  is  probably  but  a  special  development  of  the  surrounding  cells  of 
the  fundamental  system. 


210  TRILLIUM. 

c.      The  several  tissues  of  the  bundle. 

i.     The   phloem,    of    long,   thin-walled,    uniform 

cells.     Draw, 
ii.     The  vessels,  of  various  sizes  and  kinds.     Draw 

some  of  each. 

iii.  The  wood  parenchyma,  considerably  like  the  bast 
parenchyma,  but  in  its  best  development  with 
thicker  walls,  and  more  evident  somewhat 
oblique  end  walls.  Draw. 

Strip  some  epidermis  from  the  surface  of  the  stem,  and 
under  low  power,  notice 

10.    The  shape  and  arrangement  of   the  cells,  and  of  the 
stomata.     Draw. 

D.  THE  LEAF.  Make  a  vertical  section  near  the  middle 
of  a  foliage  leaf,  at  right  angles  to  the  principal  veins,  and 
notice 

1.  The  row  of  colorless  epidermal  cells  bounding  the  upper 
and  lower  surfaces. 

2.  Here  and  there  transverse  sections  of  the  veins.     Note 
the  depression  above,    and  the   convexity   below   the 
larger  veins. 

3.  The  mesophyll.     Note 

a.  The  layer  of  closely  set  cells  along  the  upper  side, 
palisade  parenchyma. 

b.  The  loose  irregular  tissue  on  the  lower  side,  spongy 
parenchyma. 

Under  high  power,  notice 

c.  The  shape  and  position  of  the  cells  of  the  palisade 
parenchyma. 

d.  The  shape  of  the  cells  of  the  spongy  parenchyma 
and  the  numerous  intercellular  spaces. 

e.  Contents  of  the  mesophyll  cells. 


TRILLIUM  RECUR  VA  TC'.V.  2 1 1 

4.  The  epidermis.     Note 

a.  The  shape  and  irregularity   of  the  cells   on  the 
upper  side  of  the  leaf. 

b.  The  shape  and    irregularity  of  the  cells  on  the 
lower  side,  together  with  the  shape  of 

c.  The  numerous  stomata  in  transverse  section,  when 
cut  through  the  middle,  and  when  through  the 
ends. 

5.  Draw  a  part  of  the  mesophyll  and  epidermis,  extend- 
ing from  one  side  of  the  leaf  to  the  other. 

6.  The  reins.     Selecting  a  vein  of  moderate  size,  note 

a.  The  small  epidermal  cells  on  the  upper  side,  and 
the  large  ones  on  the  lower  side,  both  more  thick- 
ened and  regular  than  elsewhere  on  the  leaf. 

b.  The  fibro-rasculiir   bundle,    with  the    xylem  area 
toward  the  upper  side,  and  the  phloem  area  toward 
the  lower  side4  :  sometimes  with 

c.  Fundamental  parenchyma   interposed   between  the 
bundle  and  the  epidermis  on  either  side. 

d.  Draw  a  vein. 

Strip  some  epidermis  from  the  upper  side  of  the  leaf, 
and  some  from  the  lower  side,  and  notice 

7.  The  shape  and  arrangement  of  the  cells  of  the  two  sur- 
faces, and  the  abundance  of  stomata.     Draw. 

E.  THE  FLOWER. 

i.    The  sepals.     Make  a  transverse  section  through   the 
middle  of  a  sepal,  and  notice 

a.      The  several  parts   and  tissues  seen  in  the  leaf. 
Draw. 

4  Note   how  this  follows  from  the    relative  positions  of    xylem  and 
phloem  in  the  stem. 


ii2  TRILLIUM. 

Strip  some  epidermis  from   the  upper  and  lower  sides, 
and  notice 

b.      The  shape  of  the  cells,  and  presence  or  absence  of 
stomata  in  each.     Draw. 

2.  The  petals.     Make  a  transverse  section   through  the 
middle  of  a  petal,  and  notice 

a.  The  several  parts  seen  in  the  leaf.     Draw. 

Strip  some  epidermis  from  the  upper  and  lower  sides, 
and  notice 

b.  The  shape  of  the  cells  and  presence  or  absence  of 
stomata  in  each.     Draw. 

3.  The  stamens.     Make  a  transverse  section  through  the 
middle  of  a  filament,  and  at  the  same  time  through  the 
middle  of  the  anther,  and  notice 

a.  The  parts  of  the  filament. 

i.  The  epidermis,  with  a  minutely  sinuous  out- 
line to  the  free  surface. 

ii.     ^ht  parenchyma  beneath. 

iii.  The  central  fibro-vascnlar  bundle,  consisting 
largely  of  xylem,  with  only  a  few  small  groups 
of  scattered  phloem  cells  on  the  more  convex 
(outer)  side. 

b.  Draw  part  of  the  filament. 

c.  The  connective,  with  tissues  like  those  of  the  fila- 
ment. 

d.  The  theca,  consisting  of 

i.     The  two  valves  usually  broken  away  at  the 

tips,  springing  from 
ii.     The  base  which  merges  into  the  connective. 

e.  The  wall  of  the  thecal  valves.    Note 

i.  The  epidermis,  like  that  of  the  filament  but 
with  numerous  stomata,  seen  in  transverse 
section. 


TRILLIUM  RECUR  VA  TUM.  2 1 3 

•  ii.     The  cndothecium,  having  its  cells  provided  with 

transverse  thickenings, 
iii.    The  broken  cells  at  the  tips,  corresponding  to 

the  broken  cells  at  the  middle  of  the  base. 
/.      The  base  of  the  theca.     Note 

i.     The  arrangement  of  the  spiral  cells, 
ii.     The  median  cavity  and  its  extent. 
g.     Draw  a  theca  in  outline,  and  fill  in  a  portion  of  the 

tissues. 
//.      The  pollen  spores.     Note 

i.     The  surface  of  the  wall,  its  roughness,  and 
the  simple,  large,  round  or  oblong  spots  to  be 
seen  upon  some  spores. 
The  wall  in  optical  section. 
Draw. 

Burst  some  spores  by  pressing  on  the  cover  glass.     Note 
iv.     The  empty  outer  layer  of  the  wall,  extine. 
v.     The  remainder  of  the  spore,  still  enveloped  by 

the  thin  intine,  roughened  like  the  extine. 
vi.     The  contents  from  broken  spores,  with  minute 
granules. 

\.    The  carpels.     In  a  transverse  section  through  the  style, 
notice 

a.  The  epidermis  and  parenchyma  like  that  of  the  fila- 
ment of  the  stamen. 

b.  The    fibro-vascular     bundle    with    apparently    no 
phloem,   elongated   to   embrace   the  cleft   of  the 
stigma. 

The  stigmatic  surfaces,  covered  with  papillae. 

In   some  of  the  pollen   spores  lodged   upon   the 

papillae,    the   developing    pollen   tubes    may    be 

detected. 

Illustrate  with  drawings. 


214  TRILLIUM. 

In  a  transverse  section  through  the  compound  ovary  notice, 
under  low  power, 

f.  The  uniform,  continuous  epidermis. 

g.  The  loose  parenchyma  tissue  of  the  wings  and  walls. 
h.      The  fibro-vascular  bundles  under  the  sinus  between 

each  pair  of  wings,  and  the  groups  in  the  placen- 
tae.    The  latter  give  off  branches  to 
/.       The  ovules,  placed  back   to   back   in   the   ovarian 
cavities.     Note 
i.    The  thick  stalk,  funiculus,  joined   to  the  side 

of  the  ovule,  quite  inverting  it  (anatropous]. 
ii.    The  two  coats  of  the  ovule,  the  inner  protruding 

from  the  outer, 
iii.    Draw. 

iv.    If  a  section  passing  through  the  center  of  an 
ovule   has  been   obtained,    note  the  nucellus 
within  the  inner  coat,  and 
v.     In  the  center  of  the  nucellus  the  small  embryo 

sac. 

vi.     Draw. 

Under  high  power,  notice 
/       The  epidermis  and  loose  parenchyma  at  the  base 

of  a  wing.     Draw. 
k.      The  nbro-vascular  bundle  of  the  wall,  showing  a 

little  phloem  only  on  the  outer  side.     Draw. 
/.      The  parenchyma  and  fibro-vascular  bundles  of  the 

placentae.     Draw  a  part. 

m.  Where  the  section  has  passed  through  the  center 
of  an  ovule,  note  the  similarity  of  the  cells  of  all 
the  parts.  Draw. 

F.  THE  FRUIT.  So  little  change  has  taken  place  in  the 
growth  of  the  fruit  that  it  is  only  necessary  to  study  the 
minute  anatomy  of 


TRILLIUM  RECUR  VA  TUM.  2  1  5 

i.  The  seed.  Make  several  sections  in  succession  from 
the  base  of  the  seed,  and  an  additional  section  from  the 
middle,  all  at  right  angles  to  the  longer  axis  of  the 
seed.  Note  in  the  latter,  under  low  power, 


The   colorless  tissue,  filled  with  reserve  /<?#</  mate- 
rial, radiating  from  the  center  of  the  seed. 
The  thin  brown  testa. 

The  large-celled  tissue  of  the  strophiole,  through 
the  middle  of  which  passes  a  fibre-vascular  bundle 
belonging  to  the  funiculus. 
In  the  sections  from  the  base  of  the  seed,  note 
J.      The  group  of  small  cells  lying  in  a  cavity  on  one 

side  the  center,  the  section  of  the  embryo. 
Under  high  power,  notice 

e.      The  several  sections  of  the  embryo.     Draw. 
In  the  section  from  the  middle  of  the  seed,  notice 
/.      The  colorless  tissues  of  the  center. 
g.      The  tissues  of  the  testa. 

i.     The  outer  layer  of  oblong  cells. 
ii.     An  inner  layer  of  more  elongated  cells. 
iii.     Within   this,   very  delicate   cells,   not   easily 
made  out. 
h.      Draw  some  of  the  colorless  cells,  with  adjoining 

testa. 

/.      The  tissue  of  the  strophiole.     Draw. 

Take  a  surface  slice  from  the  seed,  and  notice 

j.      The  shape  of  the  surface  cells.     Draw. 

ANNOTATIONS. 

The  most  notable  advance  in  Trillium,  so  far  as  its 
gross  anatomy  is  concerned,  is  the  development  of  a 


2i6  TRILLIUM. 

complete  flower.5  The  so-called  flower  of  Atrichum 
differs  essentially  from  a  true  flower  in  bearing  the  pri- 
mary sexual  organs  (antheridia  and  archegonia)  directly 
upon  the  axis  of  the  flower.  In  true  flowers  asex- 
ual spore  structures  first  arise  in  the  shape  of  pol- 
len spores  and  embryo  sac,  which  in  turn  give  rise  to 
the  primitive  sexual  organs  as  naked  cells  within  these. 
The  first  true  flowers  are  met  with  in  Pinus,  in  which 
they  have  no  envelopes  ;  in  Avena  there  is  either  no 
perianth,  or  a  very  poorly  developed  one,  just  as  we 
choose  to  regard  the  palet  and  lodiculesas  such  or  not ; 
but  in  Trillium  there  is  a  typical  perianth.  The  flower 
is  composed  of  sets  of  modified  leaves  symmetrically 
clustered  at  the  apex  of  a  short  axis.  The  outermost 
and  lowest  whorl  (calyx)  of  leaf-like  sepals,  a  second 
whorl  (corolla)  of  colored  petals,  then  two  whorls 
of  stamens  (andrcecium),  and  a  central  and  uppermost 
whorl  of  carpels  (gynoecium),  all  standing  upon  the 
broadened  apex  of  a  branch  (receptacle)  may  be  taken 
to  fairly  represent  a  typical  flower.  The  order  given 
not  only  expresses  the  order  of  occurrence  upon  the 
receptacle  but  also  the  order  of  development ;  and  the 
type  number,  three,  so  characteristic  of  monocotyle- 
dens,  should  be  borne  in  mind  (see  fig.  i). 

The  perianth  is  an  arrangement  for  protection  both 
in  bud  and  blossom,6  while  in  the  latter  stage  the  cor- 
olla becomes  in  addition  a  device  for  attraction.7 


5  For  a  concise  account  of  the   homology  and  nomenclature   of   the 
parts  of  a  flower  see  Sachs,  Text-book,  2nd  Eng.  ed. ,  p.  490. 

6  Cf.Kerner,  Flowers  and  their  Unbidden  Guests. 

7  Cf.  Gray,  Struct.  Bot.,  p.  215,  etseq.:    Darwin,  Pert,  of  Orchids  ; 
Effects  of  Cross  and  Self-fertilization  ;  Forms  of  Flowers  etc. 


TRILLIUM  RECUR  VA  TUM.  2 1 7 

While  this  is  generally  true  throughout  phanerogams, 
there  are  cases  in  which  the  calyx  becomes  attractive, 
and  other  cases  in  which  the  calyx  and  corolla  have  so 
far  lost  their  original  functions  that  they  neither  attract 
nor  protect. 

In  the  blended  carpels,  forming  the  pistil  which  in- 
closes the  ovules,  we  have  the  characteristic  feature  of 
angiosperms  as  distinguished  from  gymnosperms.  In 
Avena  the  ovule  is  adherent  to  the  wall  of  the  ovary, 
but  in  Trillium  it  is  distinct;  the  whole  after  fertilization 
forming  the  fruit  with  its  inclosed  seeds.  Each  carpel  is 
an  infolded  leaf,  bearing  the  ovules  upon  its  edges 
(see  fig.  11).  Each  should  normally,  then,  contain  two 
rows  of  ovules,  corresponding  to  the  right  and  left 
margins  of  the  leaf,  as  in  fact  is  the  case  in  Trillium. 
These  lines  of  attachment,  the  theoretical  leaf  margins, 
are  known  as  placentae.  The  upper  part  of  the  carpel- 
lary  leaf  is  generally  modified  to  form  a  long  or  short 
style,  while  the  stigma  is  a  surface  formed  of  cells  se- 
creting a  viscid  fluid,  and  more  or  less  modified  for  the 
reception  and  retention  of  pollen.8 

The  nucellus  is  the  part  of  the  ovule  to  appear  first, 
followed  by  the  inner  and  outer  integuments  in  the  order 
named  (basipctal).  Concerning  the  homology  of  the 
ovule  there  has  been  and  still  is  much  discussion,  and  the 
student  desiring  to  pursue  the  subject  must  look  to  its 
extensive  literature.9  The  anatropous  ovule  of  Tril- 

8  For  discussion  of  the  pistil  and   carpel,  and  references  to   the  litera- 
ture of  the  subject,  see  Gray,  Struct.  Bot.,  pp.  166  (with  footnotes),  259, 
et  seq. 

9  Gray,  Struct.    Bot.,    pp.     267,    282;    Eichler,    Bluthendiagramme, 
part  II,  page  xv;  Warming,    De  1'Ovule,  Ann.  Sci.  Nat.,  ser.   6,  v,   p. 
177  ;  Van  Tieghem.  op.  cit.,  ser.  5,  xii,  p.  312  ;  Sachs,  Text-book,  2nd 
Eng.  ed.,  pp.  492,  570,  etc, 


218  TRILLIUM. 

Hum  may  be  mentioned  as  by  far  the  most  common 
form.. 

As  in  Adiantum,  the  main  axis  of  Trillium  is  subter- 
ranean, horizontal  and  thickened,  forming  a  rootstock, 
a  protective  measure  which  in  this  case  is  correlated 
with  spring  blooming  and  a  long  period  of  rest.  The 
aerial  part  of  Adiantum,  however,  is  a  leaf,  while  in 
Trillium  it  is  a  branch,  the  "  root-leaves  "  being 
reduced  to  membranous  scales  on  the  rootstock.  A 
single  branch  (rarely  two)  is  sent  above  ground  each 
season,  and  a  series  of  corresponding  annual  scars  may 
frequently  be  seen  upon  the  stem.  In  the  meantime 
the  terminal  bud  of  the  latter  continues  to  develop 
and  to  thrust  its  way  through  the  soil,  protected  in 
this  root-like  habit  by  a  special  modification  of  bud- 
scales. 

Probably  the  most  exceptional  character  of  Trillium 
is  the  venation  of  its  foliage  leaves,  which  is  of  the 
netted  type,  instead  of  the  parallel  venation  most 
characteristic  of  monocotyledons,  as  in  Avena.  Among 
net-veined  leaves  they  are  palmate,  a  type  which  pro- 
duces a  broad  expanse  of  surface,  very  favorable  for  the 
accomplishment  of  leaf  work.  In  this  way  Trillium  has 
secured  a  large  exposure  of  surface  to  air  and  sunlight 
for  a  plant  so  low  in  stature,  and  generally  deeply  sunk 
in  vegetable  debris. 

The  primary  root-structure  is  quite  uniform  in  all 
plants,  consisting  of  epidermis  (or  a  piliferous  layer), 
cortical  parenchyma,  and  a  central  nbro-vascular  cylin- 
der. In  the  central  cylinder  xylem  and  phloem  masses 
alternate  with  each  other,  the  intervening  spaces  being 
occupied  by  parenchyma  (forming  a  radial  bundle) ;  sur- 


TRILLIUM  RECUR  VA  TUM.  219 

rounding  all  is  a  layer  of  parenchyma,  the  pericambium, 
and  outside  of  this  a  single  layer  of  modified  cortical 
cells,  the  bundle  sheath  or  endodermis.  Rootlets  of 
most  cryptogams  originate  from  the  bundle  sheath, 
while  in  phanerogams  they  usually  come  from  the  peri- 
cambium.10  In  the  radiating  lines  of  tracheary  vessels 
it  will  be  noticed  that  the  larger  vessels  are  toward  the 
center,  the  smaller  spiral  vessels  being  peripherally 
placed,  thus  reversing  the  order  of  the  stem.11 

The  stem  is  very  much  modified  by  becoming  a  food 
reservoir.  The  epidermis  is  poorly  limited,  often 
scarcely  distinguishable  from  the  adjacent  cortical 
parenchyma  ;  the  parenchyma  of  the  fundamental 
system  is  greatly  developed  and  filled  with  starch  ; 
while  the  fibro-vascular  bundles  are  reduced  and 
irregular  in  their  course.  In  most  cases  the  bundles 
bend  outwards,  and  such  are  evidently  leaf-traces,1* 
though  they  have  lost  all  definite  connection  with  the 
accompanying  scale-like  leaves. 

The  terminal  bud  of  the  stem  is  large  and  its  parts 
very  distinct.  It  is  taken  to  represent  in  our  series  a 
typical  terminal  bud  of  phanerogams.  A  section 
reveals  the  fact  that  the  growing  point  (piinctum  vege- 
tationis)  consists  of  a  group  of  cells,  in  place  of  the 
single  apical  cell  of  cryptogams,  and  the  forming  tis- 
sues diverge  from  it  in  well  defined  lines.  The  three 
typical  regions  of  the  stem  originate  from  different 
regions  of  this  primary  meristem,  so  that  they  do  not 

10Prantland  Vines,  Text-book,  p.  51;  Strasburger,  Bot.  Pract.,  p.  276. 

11  Cf.  Goodale,  Physiol.  Bot.,  p. no,  et  seq. ;  Prantl   and  Vines,  Text- 
book, p.5i;DeBary,  Comp.  Anat.,  p.  348. 

12  Cf.  Prantl  and  Vines,  Text-book,  p.  46;  Goodale,  Physiol.  Bot.,  p. 
125;  DeBary,  Conip.  Anat.,  p.  233. 


220  TRILLIUM. 

have  a  common  origin,  but  are  distinct  from  the  first. 
Lateral  members  soon  appear  as  small  protuberances, 
which  are  rudimentary  leaves,  branches,  or  roots,  those 
nearest  the  apex  being  the  youngest.  The  axis 
remains  so  short  that  the  lower  leaves  overlap  the 
growing  point,  and  in  the  case  of  this  underground  stem 
thicken  and  coalesce  at  their  tips,  forming  a  continuous 
and  firm  sheath,  thus  performing  the  same  office  of  pro- 
tection for  the  rootstock  that  the  root-cap  does  for 
roots.  In  the  same  Trillium  bud  may  be  seen  the 
essentially  different  mode  of  development  of  the  root 
and  branch,  the  former  being  endogenous  and  pushing 
its  way  through  the  overlying  tissues,  the  latter  exog- 
enous,18 blending  with  the  surface  tissues  of  the  stem. 

The  branch,  or  aerial  stem,  is  remarkable  for  its  sin- 
gle long  internode.  The  fibro-vascular  bundles  are 
rather  poorly  developed,  the  monocotyledonous  stem 
bundle  being  more  typically  represented  in  Avena.  In 
Trillium,  however,  are  seen  such  monocotyledonous 
characters  as  the  isolation  of  the  bundles  within  an 
abundant  fundamental  parenchyma,  the  well-marked 
phloem  and  xylem  areas  with  no  intervening  cambium 
(closed  bundles),  and  an  occasional  development  of  an 
external  sheath.14 

The  histology  of  the  leaf  is  in  general  much  the 
same  as  in  the  majority  of  leaves  ;  it  differs  from  Avena 
in  the  presence  of  a  much  better  developed  mesophyll. 
A  broader  expanse  of  leaf  tissue  necessitates  a  greater 
branching  of  the  supporting  and  conducting  fibro-vas- 
cular system,  and  a  better  differentiation  of  leaf  sur- 

18  Prantl  and  Vines,  op.  cit.,  p.  23. 
14  Prantl  and  Vines,  op.  cit.,  p.  58. 


TRILLIUM  RECCKTA ruM.  2*1 

faces.  Hence  the  palisade  and  spongy  parenchyma 
are  quite  distinct,  and  the  large  intercellular  spaces  of 
the  latter  have  more  frequent  connection  with  the 
outer  air  through  stomata.  The  fact  that  in  the 
fibre-vascular  bundles  of  leaves  the  xylem  is  always  on 
the  upper  side,  and  the  phloem  on  the  lower,  should 
be  recognized  as  necessitated  by  the  relation  which 
they  hold  to  the  same  regions  in  the  stem. 

In  the  ovary  the  distribution  of  fibro- vascular  bun- 
dles and  the  relative  positions  of  phloem  and  xylem 
are  most  interesting  and  suggestive.  The  single  bun- 
dles in  the  outer  walls  have  the  phloem  toward  the 
outside  (the  lower  surface  of  the  carpellary  leaf),  and 
the  xylem  toward  the  inside.  But  the  inner  group  of 
bundles  in  the  ovarian  partitions  have  their  arrangement 
reversed,  the  phloem  being  on  the  inside  (toward  the 
center  of  the  flower)  and  the  xylem  on  the  outside  16 
(see  fig.  10).  This  is  readily  accounted  for  by  the  in- 
folding of  the  carpellary  leaves  (see  fig.  1 1). 

The  walls  of  the  ovary  show  also  a  region  of  very 
loose  spongy  tissue,  developed  in  the  mesophyll  of  the 
carpellary  leaf,  and  extending  into  the  style,  the  con- 
ducting tissue,  "  which  serves  as  a  path  of  least  resist- 
ance for  the  penetrating  pollen  tubes."  18 

15  Cf.  Goodale,  Physiological  Botany,  p.  173. 

16  Goodale,  Physiol.  Bot  ,  p.  172. 


SHEPHERD'S  PURSE. 
Capsella  Bursa-pastoris  Moench. 

PRELIMINARY. 

THIS  plant,  chosen  to  represent  the  highest  develop- 
ment of  plant  life,  is  of  European  origin,  but  has 
become  abundant  in  this  country  and  elsewhere,  being 
one  of  those  vigorous  foreign  species  which  hasten  to 
take  possession  of  any  cleared  or  cultivated  land.  It  is 
found  everywhere  around  dwellings,  and  in  fields  and 
waste  grounds.  It  has  not  only  the  advantage  of  uni- 
versal distribution,  but  also  of  continuous  growth 
throughout  most  of  the  year,  even  a  few  warm  days  in 
winter  calling  it  into  bloom.  One  who  does  not  already 
know  the  plant  can  recognize  it  from  the  fact  that  it  is  a 
low,  quite  insignificant  herb,varying  in  height  from  five  to 
fifty  centimeters  (two  inches  to  a  foot  or  two),  with  a  ro- 
sette of  rather  narrow  jagged  root-leaves  often  lying  flat 
upon  the  ground,  much  smaller  scattered  stem-leaves, 
and  very  small  white  flowers  constantly  opening  at  the 
summit  of  the  branches,  and  producing  small  triangular 
rather  heart-shaped  pods  below  (see  fig.  6).  It  is  most 
abundant  in  spring  and  early  summer,  but  can  be  found 
in  bloom  throughout  the  warm  months,  and  may  be 
grown  in  the  green-house  for  use  in  winter. 


CAPSELLA  BURSA.PASTORIS.  223 

The  materials  needed  for  studying  are  alcoholic  (or 
fresh)  specimens  of  roots,  stems,  leaves,  flowers,  and 
pods  ;  fresh  specimens  of  flower  buds  ;  and  potassic 
hydrate. 

LABORATORY  WORK. 
GROSS  ANATOMY. 

A.  GENERAL  CHARACTERS.     Note 

1.  The  main  axis,  consisting  of  a  root  and  stem. 

2.  Three  kinds  of  branches  : 

a.      One  on  the  root,  rootlets. 

/>.      Another  on  the  stem  and  simply  repeating  it,  long 

or  very  short,  or  represented  by  small  buds. 
f.      The   third  on  the  upper  part   of  the   stem,  each 

bearing  a  single  flower,  pedicels. 

3.  The  position  of  the  stem  branches  with   reference  to 
the  stem  leaves,  axillary. 

4.  The  nodes  and  internodes  of  the  stem,  as  indicated  by 
the  insertion  of  the  leaves. 

5.  The  absence  of  lateral  appendages  on  the   root  or  its 
branches  ;  those  of  the  stem  and  its  branches  appear- 
ing as  foliage  and  flower  parts. 

6.  The  absence  of  leaves  or  bracts  subtending  the  pedi- 


cels. 


B.     THE    ROOT.     Clean  thoroughly,  immerse   in  water 
over  a  dark  surface,  and  note 

1.  The  arrangement  of  the  branches  (rhtzotaxy). 

2.  The  thickened  whitish  tips  of  uninjured  rootlets. 

1  A  notable  peculiarity  of  the  order  Cruel/era,  of  which  Capsella  is  a 
member, 


224  SHEPHERD* S  P  URSE. 

3.  Color  as  contrasted  with  that  of  the  growing  stem. 

4.  The  root-hairs  near  the  tips  of  rootlets. 

Make  transverse  and  longitudinal  sections  of  a  medium 
sized  root  and  note  the  presence  and  relative  importance  of 

5.  The  three  tissue  regions  : 

a.  The  thin  peripheral  or  cortical  region. 

b.  The  large  axial  or  central  cylinder,  in  which  radi- 
ating lines  formed  by  large  ducts  can  usually  be 
seen  in  the  transverse  sections. 

c.  A  region  of  loose  colorless  cells  between  the  other 
two  regions. 

Peel  the  outer  layers  from  a  branching  root,  and  notice 

6.  The  axis  of  each  rootlet  remains  attached  to  the  axis 
of  the  main  root. 

C.  THE    STEM.     Note 

1.  Mode  of  branching. 

2.  Surface  markings. 

3.  The  relative  lengths  of  internodes. 

4.  Axillary  branches  or  buds. 

Make  a  transverse  section  and  note 

5 .  Three  regions  : 

a.  The  peripheral  or  cortical  region. 

b.  The  narrow  median  or  fibro-vascular  region. 

c.  The  axial  or  pith  region? 

6.  The  fibro-vascular  bundles.     Note 

a.  Shape  and  relative  size. 

b.  The  cut  ends  of  the  tracheary   vessels,   as   holes 
through  the  bundles. 

*  Not  present  in  the  root. 


CAPSELLA  BURSA-PASTORIS.  225 

7.  Draw  the  section. 

Make  a  longitudinal  section  through  a  branch  and  leaf- 
bearing  node,  and  note 

8.  The  three  regions,  as  well  as 

9.  Their  relation  to  the  leaf  and  branch. 
10.    Illustrate  with  diagram. 

D.  THE  LEAF.     Note 

1.  Two  sorts  of  leaves  : 

a.  Root-leaves,  clustered  at  the  base  of  the  stem. 

b.  Stem-leaves. 

2.  Leaf  arrangement  (p/iy/lotaxy).     Observe  that  an  imagi- 
nary line  connecting  the  insertions  of  successive  stem 
leaves  is  a  spiral.     Discover  the  number  of  times  the 
spiral  encircles  the  stem,  and  the  number  of  leaves  it 
passes,  before  reaching  a  leaf  standing  directly  over  the 
first.3 

3.  Leaf  parts  ;  in  the  root-leaves  a  blade  and  leaf-stalk  or 
petiole,  in  the  stem-leaves  simply  a  sessile  blade. 

4.  Leaf  shapes  and  sizes,  the  great  variety.     Draw  a  series 
of  the  most  characteristic. 

5.  Leaf  surfaces  j    differences   between  the    upper  and 
lower.     Notice 

a.  Simple  hairs. 

b.  Stellate  hairs. 

6.  Distribution  of  the  veins,  and  their  relation  to  the  teeth. 

7.  The  uncoiling  of  the  spiral  threads,  when  the  leaves  are 
broken  by  careful  stretching. 

3  The  student  may  find  it  easier  to  substitute  a  thread    for  the    imagi- 
nary line,  and  must  also  allow  for  any  twisting  of  the  stem. 


226  SHEPHERD' S  P URSE. 

E.  THE  FLOWER.     Note 

1.  The  four  sets  of  organs  and  the  number  of  parts  in  each. 

2.  The  receptacle,  the  enlarged  end  of  the  stem. 

3.  The  sepals. 

a.  The  number  of  whorls. 

b.  The  shape. 

c.  The  color  in  fresh  specimens. 

d.  Draw  a  single  sepal. 

4.  1\&  petals. 

a.  The  number  of  whorls. 

b.  The  j^a/*. 

<r.      The  color  in  fresh  specimens. 
</.      Draw  a  single  petal. 

5.  The  stamens. 

a.  The  number  of  whorls,  and  number  of   stamens  in 
each. 

b.  The   lengths  and   positions    compared    with    one 
another. 

c.  The   position   of  the  long  pairs  and  short  single 
stamens  with  reference  to  the  petals. 

d.  The  four  greenish  elevations  on   the  receptacle, 
nectaries,  alternating  with  the  paired    and    single 
stamens. 

c.      The  filament,  to  the  tip  of  which  is  attached 
/.      The  anther.     Note 
i.     The  two  theca. 
ii.     The  very  narrow  connective. 
iii.     The  lines  of  dehiscence  (best  seen  in  the  anther 

of  an  advanced  bud), 
iv.     The  shape  of  apex  and  base. 
v.     The  different  appearance  of   the   inner  and 
outer  faces. 


CAPSELLA  BURSA-PASTORIS.  227 

vi.     With  a  needle  gently   break  open  the  thecae, 
and,  mounting  dry,  note  the  abundance,  color, 
and  pulverulence  of  \hz  pollen. 
,i,r.      Draw  an  uninjured  stamen. 

6.  The//jf///.     In  a  just  opened  flower,  note 

(7.  The  shape. 

b.  The  three  parts,  stigma,  style,  and  ovary. 

c.  The  oi'ulfs. 

d.  Draw  an  uninjured  pistil. 

7.  Construct  a  diagram  (like  fig.   i)  to  show  the  relation 
of  the  parts  of  the  flower  to  each  other. 

F.  THE   FRUIT.     Taking  the   oldest  well-formed   pod, 

note 

1 .  The  shape. 

2.  The  median  ridge  of  each  flattened  face  extending  into 
the  persistent  style. 

In  a  transverse  section  of  a  pod  note 

3.  The  partition  formed  by  the  inward  projection    of  the 
two  placental 

Open   a   pod   by  pulling  away   the   two  valves  from  the 
ridge,  and  note 

4.  The  shape  of  the  valves. 

5.  The  membranous  partition. 

6.  The  seeds.     Note 

a.  The  funiculus  and  its  attachment. 

b.  The  roughened  surface,  best  seen  in  dry  seeds. 

c.  The  shape,  appearing   curved   upon    itself,   campy- 
lotropous. 

d.  Draw  a  seed  showing  its  attachment. 


2  2  8  SHEPHERD' S  P  URSE. 

At  the  free  end  of  as  old  a  seed  as  possible,  tear  the  seed- 
coats  slightly,  and  by  careful  pressure  force  out 

e.  The  embryo.     Make  out  the  relations  of 

i.     The  seed-leaves,  the  cotyledons. 
ii.     The  initial  stem,  the  caulicle. 

f.  Draw  the  embryo. 

In  a  transverse  section  across  the  long  axis  of  the  seed, 
note 

g.  The  seed-coats. 

h.      The  cut  faces  of  the  two  cotyledons,  rather  flat 

and  in  contact  with  each  other. 
i.       A  section  of  the  caulicle,  at  the  narrower  end  of 

the  section,   and  lying  against  the  back  of   one 

cotyledon  (incumbent). 
j.       Diagram  the  section. 

MINUTE  ANATOMY. 
A.  THE  ROOT. 

i.    The  rootlets.     Remove  some  of  the  smallest  rootlets, 
examine  with  a  high  power,  and  note 

a.  In  complete  rootlets,  the  root-cap. 

b.  Behind   the   root-cap   the   central  cluster   of  mer- 
istematic  cells,  from  which  diverging  rows  of  cells 
pass  off,  gradually  merging  into 

c.  The  permanent  tissues  of  the  rootlet. 

d.  The  root-hairs  ;  the  portion  of  the  root  on  which 
found. 

e.  Make  a  diagram  of  the  tissues  of  the  root-tip,  and 
also  draw  some  root-hairs  accurately. 

Make  a  transverse  section  of  a  very  small  rootlet,4  examine 

4  Secondary  changes  take  place  so  rapidly  in  the  roots  of  Capsella,  that 
some  difficulty  may  be  experienced  in  finding  one  with  typical  primary 
root  structure  ;  very  young  rootlets  should  therefore  be  selected  for  exam- 
ination. 


CAPSELLA   BURSA-PASTORIS.  229 

with  a  high  power,  and  note 

/.      A  peripheral  region,  consisting  of  the  epidermis,8 

and  a  few  layers  of  hypodermal  cells. 
g.      A  median  region  of  colorless  cells,  the  cortex. 
//.      Within   this  a  single  row  composed  of  somewhat 
smaller,  more  closely  packed  cells,  the  bundle  sheath. 
i.       The  space  inclosed  by  the  sheath  entirely  occupied 
by  \\\Q  fibro-vascular  region,  in  which  note 
i.     The  two  xylem  masses,  placed  with  their  inner 
ends  of  larger  cells  in  contact,  thus  dividing 
the  region  into  similar  halves  (binary]. 
ii.     The  two  phloem  masses,  placed  right  and  left 

of  the  xylem. 

iii.     A  limited  amount  of  parenchyma,  separating 
the  xylem  and  phloem  portions    from    each 
other,  and  both  from  the  bundle  sheath. 
j.       Draw  the  whole  section. 

A  series  of  ^transverse  sections  of  larger  and  larger  root- 
lets will  show  secondary  changes,  characteristic  of  dicoty- 
ledons, up  to 

2.    The  main  shaft.     Make  a  transverse  section,  examine 
with  a  low  power,  and  note 

a.  The  entire  disappearance  of  epidermis. 

b.  The  cortical  parenchyma. 

c.  The  fibro-vascular  cylinder. 
Using  a  high  power,  note 

d.  The  cortical  parenchyma  arranged  in  radiating  lines, 
from   the   tangential   and    radial   division   of    its 
meristem  cells.     The  outer  layers  may  be  com- 
posed of  thin-walled,  close  set,  squarish  cells,  cork  ; 
within  which  are  often  other  layers  of  larger  cells, 
much  distorted  from  the  pressure  under  which  the 

5  The  epidermis  may  have  disappeared  even  in  a  very  small  rootlet. 


230  SHEPHERD'S  PURSE, 

root  grows.     Any  of  the  cortical  cells  may  have 
thickened  walls. 

e.  The  alternating  xylem  and  phloem  masses.     In  com- 
parison with  the  sections  under  A.  i.  note 

i.  The  increased  number  and  irregularity  of 
xylem  and  phloem  rows,  making  longer  and 
shorter  radial  rows,  quite  obscuring  the 
primitive  arrangement. 

ii.  An  almost  complete  disappearance  of  inter- 
vening parenchyma,  xylem  and  phloem  being 
in  close  contact. 

f.  Draw  a  segment  showing  the  tissues  noted. 
Make  a  radial  longitudinal  section,   and   using  a  high 

power, 

g.  Compare  thoroughly  with  the  regions  of  the  trans- 
verse section.8 

//.      Illustrate  with  drawings. 

B.  THE  STEM.     Make  a  transverse  section,  examine  with 
low  power,  and  note 

1.  Three  regions  : 

a.  Cortical  region. 

b.  Fibro-vascular  region. 

c.  Pith. 

2.  IL\&  fibrd-vascular  bundles  ;  shape  and  relative  sizes. 
Examine  with  a  high  power,  and  note 

3.  One  row  of  epidermal  cells,  with  very  thick  outer  and 
inner  walls.     Note 

a.      The  cuticle. 


6  Several  sections  will  be  needed  to  show  all  the  regions  of  the  fibro- 
vascular  area. 


CAPSELLA   BURSA-PASTORIS.  231 

b.      Sections  of  stomata. 

4.  Several  rows  vl  parenchyma  cells. 

5.  Usually  one  row  of  tolerably  large,  nearly  empty  paren- 
chyma cells,  the  bundle  sheath  (best  distinguished  in 
section  from  growing  plant). 

6.  The  masses  of  fibrous  tissue  rising  between  the  outer 

portions  of 

7.  The  fibre-vascular  bunJlcs  ;  selecting  one  of  the  largest 
of  these,  note 

a.  The  arch  of  bast  fibers  ;  compare  this  region  with 
the  same  in  smaller  bundles. 

b.  Beneath  the  arch  a  cluster  of  smaller  irregular  cells, 
soft  bast. 

c.  The  trachcary  tissue  and  wood  fibers  composing  the 
xylem. 

S.    The  position  and   extent  of  the/////,  the  regularity  of 
the  cells  and  the  intercellular  spaces. 

9.    Draw  a  segment  of  the  section  containing  at  least  one 
bundle. 

Make  a  radial  longitudinal  section,  including  a  fibro-vas- 
cular  bundle,7  examine  with  a  high  power  and  note 

10.  The  epidermal  cells. 

11.  Parenchyma. 

12.  Bundle  sheath  of  squarish  cells. 

13.  The  bast  fibers,  length  and  nature  of  walls. 

14.  Soft  bast,  shape  and  walls. 

15.  Tracheary  vessels,  variously  marked. 

1  In  a  section  which  passes  between  fibre-vascular  bundles,   the  same 
regions  will  be  noted,  except  that  13,  14,  15,  16  are  replaced  by  abundant 

fibrous  tissue. 


23  2  SHEPHERD' S  P  URSE. 

1 6.  Wood  fibers,  length  and  nature  of  walls. 

17.  Pith  parenchyma,  character  of  walls. 

1 8.  Draw  the  various  tissues. 

C.  THE  LEAF.  Make  a  transverse  section  of  a  radical 
leaf  at  right  angles  to  the  midrib,  examine  with  a  high 
power,  and  note 

1.  The  epidermis,  consisting  of  one  row  of  empty  cells  on 
the  upper  and  under  surfaces  of  the  leaf.     Observe 

a.  Sections  of  stomata.     Draw. 

b.  Hairs  of  various  kinds.     Draw. 

2.  The  mesophyll,  consisting  of 

a.  An  upper  row  of  oblong  cells  with  longer  axis  at 
right  angles  to  the  plane  of  the  \zzi,  palisade  paren- 
chyma. 

b.  A  lower  region  of  rounded  loosely  aggregated  cells, 
spongy  parenchyma,  with   large  and  small  intercel- 
lular spaces,  those  in  connection  with  the  stomata 
being  especially  large. 

3.  The  fibro-vascular  system.     In  the  section  of  the  midrib 
note 

a.  The  position  of  the  phloem  and  xylem  areas  with 
reference  to  the  leaf  surfaces.8 

b.  The  tissues  in  each  as  compared  with  those  of  the 
stem  bundles. 

In  sections  of  the  veinlets  note 

c.  The  tissues  that  persist. 

4.  Draw  a  transverse  section  of  the   leaf,   illustrating  all 
the  observed  facts. 

8  Note  how  these  positions  follow  from  the  relative  positions  of  xylem 
find  phloem  in  the  stem, 


CAPSELLA   BURSA-PASTORIS.  233 

Mount  a  portion  of  the  epidermis  of  both  surfaces  of  the 
leaf,  and  note 

5.    The  epidermal  tissue. 

a.  Shape  of  the  cells. 

b.  Hairs  of  two  kinds. 

c.  Stomata,  comparative  abundance  on  the  two  sur- 
faces. 

d.  Often  dark  sheaf-like  masses  of  raphides,  torn  out 
from  underlying  cells. 

e.  Illustrate  with  drawings. 

D.    THE  FLOWER. 

1.  The  sepals.     Mount  a  sepal,  examine  with  a  high  power, 
and  note 

a.  Venation. 

b.  Epidermal  cells,  their  shape  and  striation. 

c.  Presence  or  absence  of  stomata. 

d.  Make  a  drawing,  showing  these  characters. 

2.  The  petals.     Mount  a  petal,  and  note 

a.  Venation. 

b.  Epidermal  cells  of  the  tip  and  base,  their  shape  and 
striation. 

c.  Presence  or  absence  of  stomata. 

d.  Draw. 

3.  The  stamens.     Make  a  transverse  section  through  a  fil- 
ament and  also  through  an  anther  of  an  advanced  bud,9 
examine  with  a  high  power,  and  note 

a.      The  structure  of  the  filament. 
i.     The  epidermis, 
ii.     The  parenchyma  beneath. 

9  This  can  best  be  done  by  making  a  section  of  the  entire  bud. 


234  SHEPHERD'S  PURSE. 

iii.     The  fibro-vascular  bundle,  comparing  its  tis- 
sues with  those  in  the  stem  bundles. 

b.  The  two  theccz,  each  consisting  of  two  valves. 

c.  The  wall  of  the  valves,  consisting  of 

i.     The  epidermis. 

ii.  The  endothecium>  an  elastic  inner  row  of  spir- 
ally thickened  cells. 

d.  Draw  a  section  of  a  theca  showing  its  tissues. 

e.  The  pollen.     Note 

i.     The  surface  of  the  wall. 

ii.  The  two  layers  of  the  wall :  the  extine  col- 
ored and  with  thin  spots  ;  the  intine  thin  and 
colorless. 

By  careful  pressure  upon  the  cover  glass,  there  can  be 
seen 

iii.     The  intine  unbroken,  but  protruding  through 
one   of   the   thin   spots    in    the    extine,   the 
true  character  of  the  wall  becoming  thus  very 
obvious, 
iv.     The  minutely  granular  contents. 

4.  The  pistil.  Mount  a  slice  from  the  surface  of  the 
stigma  and  also  a  transverse  section  of  the  ovary,  both 
cleared  with  potash,  and  note 

a.  The  stigma. 

i.     Its  surface,  with  pollen  tubes  sometimes  pene- 
trating it. 
ii.     Draw. 

b.  The  ovary. 

i.     The  epidermal  cells, 
ii.     The  character  of  the  mesophyll. 
iii.     The  fibro-vascular  bundles,  their  position  and 

tissues, 
iv.     The  structure  of  the  placentae. 


CAPSELLA   BURSA-PASTORIS.  23$ 

v.     The  structure  of  the  false  partition, 
vi.     Draw. 

c.  The  ovules. 

i.     In  favorable  sections  the  pollen  tubes  maybe 
seen  entering  the   ovules.     These  are  easily 
recognized,  as  the  tube  breaks  off  some  dis- 
tance from  the  micropyle. 
ii.     The   fibro-vascular   bundle  of  the  funiculus 

terminating  in  the  ovule, 
iii.    The  two  integuments,  distinct  from  each  other 

beyond  the  bend. 

iv.     The  nucellus,  containing  a  large  cavity,  the 
embryo  sac,  which  follows  the  curve  of    the 
ovule.     Within  the  embryo  sac 
v.     The  embryo,  in  various  stages  of  development, 
vi.     Draw,  showing  all  the  above  facts. 
The  following  phases  in  the  development  of  the  embryo 
can  not  be  seen  in  alcoholic  specimens,  but  may  readily  be 
traced  in  fresh  ones  by  the  use  of  potash  as  a  clearing  agent. 

d.  The  embryo.     Mount  some  cleared  ovules  from  an 
advanced  but  unopened  bud,  press  slightly  upon 
the  cover  glass,  and  note 

i.     The  large  curved  embryo  sac. 

ii.     In  the  end  of  the  sac  nearest  the  micropyle,  a 

roundish  or  oblong  cell,  the  oosphere. 
iii.     At  the  opposite  end  of  the  sac,  a   mass  of 

cells  projecting  into  it. 

Mount  ovules  from  an  open  flower,  treat  as  before,  note 
iv.     In  place  of  the  oosphere  a  chain  of  cells,  the 
pro-embryo,  with  the  basal  cell  usually  much 
swollen  and  with  a  group  of  cells  at  the  free 
end  of  the  chain,  the  forming  embryo™ 

10  The  endosperm,  which  develops  rapidly  in  angiosperms  after  fertili- 
zation, is  too  transient  in  this  case  to  make  out  satisfactorily. 


236  SHEPHERD'S  PURSE. 

From  this  point  the  development  of  the  embryo  may  be 
traced    with  greater   or  less  particularity,    by    examining 
ovules  in  various  stages  of  advancement,  until  the  following 
condition  is  seen  in  seeds  from  a  young  pod  : 
v.     The  pro-embryo  has  disappeared. 
vi.     The  embryo  nearly  fills  the  embryo  sac,  the 
cotyledons    beginning    almost    exactly  at   the 
bend, 
vii.     Make  drawings  illustrating  this  development. 

E.  THE  FRUIT.     Make  a  tranverse  section  through  as 
old  a  fruit  as  possible,  clear  with  potash,  and  note 

1.  The  nature  of  the  epidermis,  mesophyll,  fibro-vascular 
bundles,  placentae  and   partition,  compared  with  that 
studied  in  the  ovary. 

2.  The  seed.     In  transverse  sections  of  seeds  note 

a.  The  testa,  its  color  and  structure. 

b.  The  thin-walled  tissue  filled  with  food  material. 

c.  The  cotyledons,  the  nature  of  their  tissues  as  com- 
pared with  those  of  the  leaf. 

d.  The    caulicle,    its  structure  and   tissues  as  com- 
pared with  those  of  the  stem.     Draw. 

e.  Draw  a  complete   section   of  the  seed,   filling  in 
enough  of  the  tissues  to  indicate  their  character. 

ANNOTATIONS. 

Capsella  very  well  presents  in  a  compact  form  the 
salient  features  of  a  dicotyledon.  The  paired  cotyle- 
dons, net-veined  leaves,  four-parted  flowers,  and  con- 
tinuous fibro-vascular  zone  of  the  stem,  all  mark  it  as  a 
member  of  this  highest  group. 


CAP  SELL  A   BURSA-PASTORIS.  237 

The  primary  root  continues  the  plant  axis  below 
the  surface  of  the  ground  in  the  form  of  a  tap  root,  and 
thus  enables  the  plant  to  take  a  deep  and  firm  hold 
upon  the  soil.  Such  primary  roots  are  best  developed 
in  dicotyledons  and  gymnosperms,  remaining  small  in 
monocotyledons  and  pteridophytes. 

The  foliage,  instead  of  being  somewhat  evenly  dis- 
tributed along  the  stem  and  its  branches,  is  largely 
collected  at  the  surface  of  the  ground  in  a  cluster  of 
so-called  root-leaves.  The  toothed  and  lobed  outline 
of  the  leaves  with  reticulated  venation  is  quite  charac- 
teristic of  dicotyledons.  In  Trillium  (an  anomalous 
monocotyledon  in  this  regard)  there  was  presented  the 
palmate  type  of  net-veined  leaves,  while  in  Capsella 
we  find  the  pinnate  type,  tending  to  narrower  and 
longer  leaf  forms. 

An  exceptional  feature  of  Capsella  (and  other 
Cruciferce)  is  the  entire  suppression  of  bracts  in  the 
flower  cluster,  giving  the  pedicels  (branches)  the 
appearance  of  originating  from  the  main  axis  without 
subtending  leaves. 

The  structure  of  the  flower  is  not  typical  of  dicotyle- 
dons, in  which  the  type  would  be  better  expressed  by 
an  arrangement  like  that  of  Trillium,  after  substituting 
five  for  three  as  the  type  number.  As  a  member  of  the 
Cruciferce,  however,  Capsella  has  two  whorls  of  two 
sepals  each,  the  lower  (outer)  being  median  (in  the 
plane  of  the  axis)  and  the  inner  lateral ;  one  whorl  of 
four  petals,  alternating  with  the  .four  sepals ;  two 
whorls  of  stamens,  the  outer  and  shorter  pair  lateral, 
the  inner  and  longer  set  composed  of  four  stamens, 
arranged  in  axial  pairs(tetradynamous)  ;  and  one  whorl 


238  SHEPHERD'S  P URSE. 

of  two  carpels  laterally  placed.  There  has  been  much 
discussion  concerning  the  cruciferous  flower,  chiefly  as 
to  its  six  stamens  and  single  whorl  of  four  petals.  The 
most  natural  explanation  seems  to  be  that  which 
makes  two  the  type  number  throughout,  the  inner 
whorl  of  stamens  and  the  single  whorl  of  petals  each 
becoming  four  by  chorisis.11  The  morphological  sig- 
nificance of  the  small  glands  among  the  stamens  at  the 
base  of  the  ovary  is  uncertain.12 

The  bi-carpellary  ovary  becomes  two-celled  by  a 
membranous  outgrowth  connecting  the  two  opposite 
parietal  placentae.  This  outgrowth,  not  being  a  usual 
part  of  the  carpels,  is  considered  a  false  or  spurious 
partition.  When  the  fruit  (a  silicle)  opens,  the  two 
valves  split  away  from  this  false  partition,  to  which  the 
placentae  and  hence  the  seeds  remain  attached. 

No  part  of  vascular  plants  has  so  constant  a  charac- 
ter as  the  root.  The  root-cap  and  root-hairs,  most 
characteristic  root  structures,  are  much  alike  in  all 
cases.  The  primary  arrangement  of  the  tissues  in 
pteridophytes,  gymnosperms,  monocotyledons,  and 
dicotyledons  is  upon  the  same  plan  throughout.  The 
original  number  of  xylem  and  phloem  masses  is  quite 
limited  in  dicotyledons,  ranging  from  two  of  each  (bi- 
nary, as  in  Capsella)  to  eight,  but  is  not  constant ;  while 
in  monocotyledons  it  is  generally  larger.  In  dicotyle- 
dons and  gymnosperms  the  root  increases  in  thickness 
by  secondary  growth  which  eventually  produces  great 

11  Gray,  Struct.  Bot.,  p.  206,  with  reference  to  the  views  of  Eichler, 
Kunth,  Henslow,  and  others  ;  Strasburger,  Bot.  Pract  ,  p.  587  ;  Eichler, 
Flora,  1865,  p.  497,  and  1869,  p.  97  (both  with  plates)  ;  Bltithendia- 
gramme,  ii,  p.  200,  where  the  literature  is  cited. 

l*  Cf.  Hildebrand,  Prings.  Jahrb.,  xii,  p.  10  ;  Mttller,  ibid,  p    161. 


CAPSELLA  BURSA-PASTORIS.  239 

changes  in  the  primary  structure.  Certain  of  the  deli- 
cate parenchyma  cells  lying  between  the  xylem  and 
phloem  elements  undergo  repeated  division,  producing 
wood  and  bast  tissue.  The  layer  of  cambium  cells  thus 
begun  on  either  side  of  the  original  plate  of  xylem  soon 
unites  with  its  neighbor  at  the  ends,  and  forms  a  closed 
cambium  ring.  This  ring  has  the  properties  of  the 
cambium  layer  of  the  stem,  as  in  Pinus,  and  by  means 
of  it  the  root  is  enabled  to  increase  in  thickness 
to  any  extent.  It  does  not,  however,  as  in  the 
stem,  produce  its  phloem  exclusively  on  the  outside  and 
xylem  on  the  inside  of  the  ring,  but  they  lie  side  by 
side  in  radiating  lines,  the  number  of  these  lines 
increasing  with  the  increase  in  circumference.18 

The  fundamental  system  in  the  stem  of  dicotyle- 
dons is  much  more  differentiated  than  is  usual  in  mon- 
ocotyledons. It  is  divided  into  an  inner  and  outer 
region  by  the  fibro-vascular  system,  in  the  latter  of 
which  various  tissues  may  be  developed,  such  as  col- 
lenchyma,  fibrous  tissue,  etc.  In  the  case  of  Capsella 
the  principal  modification  of  the  parenchyma  of  the 
fundamental  system  is  the  development  of  the  abun- 
dant fibrous  tissue  (sometimes  referred  to  scleren- 
chyma),  which  embraces  the  xylem  of  the  bundles 
and  arches  between  the  phloem  areas.  In  the  fibro- 
vascular  system  the  chief  characters  of  the  dicotyle- 
donous stem  appear.  The  wedge-shaped  bundles  are 
not  scattered  through  the  fundamental  tissue,  but 
are  arranged  in  a  zone  concentric  with  the  surface  of 

13  On  the  secondary  thickening  of  roots  see  DeBary,  Comp.  Anat  ,  p. 
473  ;  Goodale,  Physiol.  Bot,  p.  113  ;  VanTieghem,  Ann.  Sci.  Nat.,  ser. 
5,  xiii,  p.  185. 


2  40  SHEPHERD' S  P  URSE. 

the  stem,  and  inclosing  the  inner  region  of  the  funda- 
mental tissue,  the  pith.  The  parenchyma  rays 
(medullary  rays)  left  between  the  bundles  may  be 
broad  or  narrow.  The  arrangement  and  course  of  the 
bundles  depend  largely  upon  the  position  of  the  leaves. 
From  each  leaf  one  or  more  bundles  enter  the  stem 
and  passing  downward  finally  become  part  of  the  fibro- 
vascular  zone.  Transverse  sections  of  the  stem  often 
cut  across  bundles  midway  in  their  course  from  the 
leaf  to  the  vascular  ring,  and  they  then  appear  as  if 
belonging  to  the  cortex.  The  bundles  are  collateral, 
with  a  cambium  layer  between  the  xylem  and  phloem, 
forming  the  characteristic  open  bundle  of  dicoty- 
ledons. In  Capsella  a  bundle-sheath  arches  over  each 
bundle,  and  frequently  becomes  continuous  around 
the  entire  fibre-vascular  zone."  In  the  xylem  the 
spiral  and  annular  vessels  are  the  oldest  and  most 
centrally  placed,  the  dotted  ducts,  the  largest  elements 
of  the  xylem,  occurring  nearest  the  phloem  15 

The  leaf  shows  the  general  dicotyledonous  charac- 
ters of  more  contorted  epidermal  cells  and  more  num- 
erous and  smaller  stomata.  The  fibro-vascular  bun- 
dles are  like  those  of  the  stem,  tracheides  replacing 
other  vascular  elements  in  the  ultimate  ramifications. 

Capsella  is  so  favorable  for  the  study  of  the 
development  of  the  embryo,  that  this  very  import- 
ant subject  has  been  deferred  until  now.  It  has 
already  been  seen  how  the  asexually  produced  pollen 
spore  (microspore),  after  falling  upon  the  papillated 

14  Pointed  out  by  Kamienski,  in  DeBary's  Compar.  Anat.,  p.  415. 

15  For  stem  structure  see  Prantl  and  Vines,  Text-book,  p.  47  ;  Bessey, 
Bot.,  p.  438  ;  Goodale,  Physiol.  Bot.,  p.  119. 


CAPSELLA   BURSA-PASTORIS.  241 

surface  of  the  stigma,  develops  a  pollen-tube  and  pene- 
trates the  tissues  of  the  style.  The  rate  of  descent  of 
the  pollen-tube  is  quite  various  in  different  plants.  In 
the  style  and  walls  of  the  ovary  there  is  usually  a 
region  of  least  resistance  to  penetration,  furnished  by 
the  delicate  "  conducting  tissue,"  or  the  style  is 
frequently  tubular  (as  in  Viola).  In  Capsella,  very 
soon  after  pollination,  an  abundance  of  pollen-tubes  is 
found  in  the  ovarian  cavity.  Some  of  them  may  be 
seen  to  have  entered  the  micropyles  of  the  ovules  and 
penetrated  to  the  nucellus. 

The  preparation  of  the  ovule  for  fertilization  has 
been  the  development,  at  the  apex  of  the  nucellus,  of 
the  embryo  sac  (macrospore),  at  the  micropylar  end  of 
which  lies  the  oosphere  (embryonal  vesicle),  accompa- 
nied usually  by  two  similar  masses,  the  synergidae.  At 
the  base  of  the  embryo  sac  appear  three  or  more  free 
cells,  the  antipodal  cells "  of  Hofmeister.  The  six 
cells  which  differentiate  into  the  antipodal  cells, 
oosphere  and  synergidae,  constitute  a  very  rudimentary 
prothallium,17  which  is  far  more  reduced  than  in  gym- 
nosperms,  but  corresponds  to  the  primary  endosperm 
of  these  plants.  The  endosperm  (of  most  text-books), 
more  properly  secondary  endosperm,  is  produced  by 
cell-formation  around  the  nuclei  arising  from  division 
of  the  definitive  nucleus  of  the  embryo  sac.18  When 


16  Strasburger,  Bot.  Pract.,  p.  522,  et  seq.;  Prantl  and  Vines,  Text- 
book, p.  205. 

17  Sachs,  Text-book,    2nd  Eng.    ed.,  p.  582,  where  a  fuller  account 
of  the  changes    preliminary  to    fertilization   in    angiosperms    may   be 
found. 

18  Sachs,  Text-book,  2nd  Eng.  ed.,  p.  585. 


242  SHEPHERD'S  PURSE. 

fertilization19  has   taken  place   a   membrane  is  devel- 
oped about  the  oosphere,  making  it  a  sexual  spore. 

By  divisions20  in  one  plane  the  oospore  at  once 
extends  toward  the  interior  of  the  ovule  as  a  chain  of 
cells,  the  suspensor  or  pro-embryo,  the  basal  cell  of 
which  becomes  large  and  bladder-like.  The  apical  cell 
at  the  free  end  of  the  suspensor,  by  repeated  division 
in  several  planes,  forms  a  cell  mass,  which  presently 
assumes  the  form  of  the  embryo.81  The  ovule  after 
various  changes  of  minor  importance  in  this  connec- 
tion becomes  at  last  a  ripe  seed. 

19  For  an  account  of  the  nuclei  of  the  pollen  spore  and  oosphere,  and 
their  union  in  the  fertilizing  act,  see  Strasburger,  Neue  Untersuchungen. 

20  For  methods  of  cell  division  in   the    developing  embryo  of  Cap- 
sella  (with   figures)  see  Bessey,  Bot. ,  p.  424  ;  Westermaier,   Die  ersten 
Zelltheilungen  im  Embryo  von  Capsella,  Flora,  1876,  p.  483. 

21  For  further  description  of  the  development  of  the  embryo  see  Gray, 
Struct.  Bot.,  p.  283  ;  Prantl  and  Vines,  Text-book,  p.  204  ;  Bessey,  Bot., 
p.  423  ;  Sachs,  Text-book,  2nd  Eng.  ed.,  p.  585. 


GLOSSARY. 


Ab-stri'c-tiou  (ab,  off :  stringo,  /  tie). 
Partial  or  complete  separation  by  con- 
traction. 

A-na't-ro-pous  (ara,  up;  Tptww,  / 
turn).  Said  of  an  inverted  ovule  or 
seed  which  has  the  rhaphe  extending 
its  whole  length. 

Aii-drcB'-ci-uiii  larjjp,  a  male  ;  OIKO«, 
a  house).  The  stamens  of  a  flower 
collectively. 

A  n  mi  lus  (annulus,  a  small  ring). 
The  elastic  ring  of  cells  around  the 
sporangium  in  ferns. 

A'n-ther  tarflrjpos,  Jlo-wery).  The  pol- 
len-bearing part  of  the  stamen. 

An-ther-i  d-i  um.  pi.  aiitheridia 
(anther;  tISos,  form).  The  male  or- 
^:in  of  the  lower  groups,  analogous  to 
but  not  homologous  with  the  anther 
of  phanerogams. 

A'li-ther-o-zoids  (anther;  ^wor,  an 
animal ;  eI6o?,  form).  The  male  re- 
productive bodies  developed  in  an- 
theridia. 

A'n-tho-tax-y  (arOos,  a  flower  ;  rafi?, 
arrangement).  The  arrangement  of 
flowers  in  a  cluster  ;  inflorescence. 

Aii-ti'p-o-dal  (ii'Ti,  over  against: 
rrous,  afoot).  Said  of  a  group  of  cells 
at  the  end  of  the  embryo-sac  furthest 
from  the  micropyle. 

A'p-i-oal  (apex,  the  top).  At  the  apex 
or  tip. 

A-po'ph-y-sis  (an-6,  from  ;  <£u'<ris,  na- 
ture). In  mosses,  an  enlargement  of 
the  pedicel  at  the  base  of  the  capsule. 

Arch-e-go'n  i-um,  pi.  archegonia 
(ap\ij.  beginning:  -yoi'jj,  offspring). 


The  female  organ  of  bryophytes  and 
pteridophytes. 

A-re'-o-la,  pi.  areolaB  (areola,  a  small 
open  space).  The  spaces  in  a  reticu- 
lated surface,  as  in  the  thallus  of 
Marchantia. 

A  s-co-spores.  The  spores  formed  in 
an  ascus. 

A  s-cus,  pi.  ascl  (a<7<co«,  a  sac).  The 
spore  sac  of  a  large  group  of  carpo- 
phytes. 

A'x-i-al.  Relating  or  belonging  to  the 
axis. 

A'x-il  (axilla,  the  arm-pit).  The  point 
just  above  the  attachment  of  a  leaf  to 
the  stem. 

A  x-is  (axis,  an  axle-tree).  The  cen- 
tral part  or  longitudinal  support  on 
which  organs  or  parts  are  arranged. 

Bast  (bass).  In  general,  the  phloem 
region  of  a  fibro-vascular  bundle  :  or, 
specifically,  the  fibers  of  the  phloem. 

Bract  (bractea,  a  thin  plate).  The 
more  or  less  modified  leaves  of  a 
flower  cluster. 

Bry-o'ph-y-ta  (,8pwoi',  moss ;  ^vrdf,  a 
plant).  A  primary  division  of  plants, 
named  from  its  principal  group,  the 
mosses.  Bry'-o-phyte  is  the  English 
equivalent. 

Bu'l  li-form  (bulla,  a  swelling).  Said 
of  enlarged  or  swollen  cells. 

Ca 1  lus  (callus,  a  callosity).  A  hard- 
ened or  thickened  place ;  technically 
used  of  the  thickening  mass  in  a  sieve- 
plate,  usually  appearing  as  a  layer  on 
each  side  of  the  plate. 


244 


GLOSSARY. 


Ca-ly'p-tra  (<a.\vmpa,  a.  cover).  In 
mosses,  the  hood  which  covers  the 
capsule. 

Ca'-lyx  (calyx,  a  cup}.  The  outer  en- 
velope of  a  flower,  composed  of  sep- 
als. 

Ca'm-bi-form.  Resembling  cam- 
bium. 

Ca'm-bi-um  (cambio,  /  exchange). 
The  meristem  cells  of  an  open  fibro- 
vascular  bundle,  lying  between  the 
phloem  and  xylem,  which  retain  the 
power  of  division. 

Cam-py-lo't-ro-pous  (/caju.7rij,  bend- 
ing; rpeirw,  /  turn\.  Said  of  an  ovule 
or  seed  which  becomes  curved  in  its 
growth  so  as  to  be  inverted. 

Ca'p-sule  (capsula,  a  small  box).  A 
dry  dehiscent  seed-vessel  (formed  of 
more  than  one  carpel) ;  or  a  similar 
spore-vessel. 

Ca'r-pei  (<cap7r6s,  fruit}.  The  con- 
stituent leaf  of  a  pistil  •  hence  either  a 
simple  pistil,  or  one  of  the  parts  of  a 
compound  pistil. 

Ca'r-pel-la-ry.    Relating  to  a  carpel. 

Car-po-go'-ni-um,  pi.  carpogonia 
(/capTTOS,  fruit  ,-yovr),  offspring).  The 
female  organ  of  carpophytes. 

Ca'r-po-phyll  (/capwos,  fruit ;  </>vAAov, 
a  leaf).  The  carpellary  leaf. 

Car-po'pli-y-ta  (xapTros,  fruit ;  <f>vT6v, 
a  plant).  A  primary  division  of 
plants,  named  from  the  sporocarp,  or 
spore-vessel,  which  is  the  result  of 
fertilization.  Ca' r-po-phyte  is  the 
English  equivalent. 

Cur-y-o'p-sis  (xapvoi',  a  nut ;  oi|us,  an 
appearance).  A  grain  ;  the  seed-like 
fruit  of  grasses. 

Cau'-li-cle  (cauliculus,  a  small  stem). 
The  initial  stem  in  an  embryo. 

Cell  (cella,  a  cell}.  The  anatomical 
unit  of  plant-structure. 

Ce'1-lu-lose  (cellulosus,  pertaining  to 
a  cell}.  The  primary  substance  of  the 
cell-wall. 

Chaff.     Small  dry  scales. 

Cha-la'-za  (x<xAa£a,  that  which  is  let 
loose).  The  part  of  an  ovule  where  in- 
teguments and  nucellus  are  confluent. 


Chlo'-ro-phyll  (xAwpos,  greenish-yel- 
low ;  ^uAAov,  a  leaf).  The  green 
coloring  matter  of  plants. 

Cho'r-i-sis  (xwptffis,  a  separating). 
Longitudinal  separation  into  two  or 
more  similar  parts. 

Ci'1-i-uni,  pi.  cilia  (cilium,  an  eye- 
lash). Marginal  hairs  ;  motile  proto- 
plasmic filaments,  as  those  of  anthero- 
zoids. 

Closed  bundle.  A  fibre-vascular 
bundle  containing  no  cambium. 

Col-la't-er-al  (con,  together ;  latus,  a 
side).  Side  by  side  ;  used  of  a  fibro- 
vascular  bundle  in  which  the  xylenj 
and  phloem  are  side  by  side  in  a  radial 
direction. 

Col-u-me'1-la  (columella,  a  small 
column).  The  persistent  axis  of  cer- 
tain spore-cases,  as  in  mosses. 

Coii-ce'n-tric  (con,  together;  centrum, 
the  center).  Technically  used  of  a 
fibro-vascular  bundle  whose  tissues 
are  arranged  concentrically. 

Co  ni'  di  o-phore  (conidia  ;  </>epw,  / 
carry).  The  stalk  upon  which  co- 
nidia are  borne. 

Co-ni'-tli-um  (gonidiutn),  pi.  conidia 
(yovr),  offspring;  eZSos,  form).  The 
asexual  spores  of  certain  groups. 

Con  jn-ga'  tion  (conjugatus,  joined 
together,  paired).  The  sexual  union 
of  similar  cells,  as  in  zygophytes. 

Con-iie'ct-ive  (connecto,  I  connect}. 
The  portion  of  the  stamen  connecting 
the  thecae. 

Co-ro'1-la    (corolla,    a  small  crown). 
The   inner    envelope    of    a    flower, 
within  the  calyx,  and   composed   of 
petals. 

Cor-pu's-cu-lum,  pi.  corpuscula 
(corpusculum,  a  little  body).  The 
archegonium-like  structures  in  the 
ovule  of  gymnosperms. 

Co'r-tex  (cortex,  the  bark).  The  rind 
or  bark. 

Co'r-ti-cal.  Relating  to  the  cortex  or 
bajk. 

Cot-y-le'-doii  (KOTV \yStav,  a  cup-shaped 
cavity).  A  primary  embryo-leaf 
borne  by  the  caulicle. 


GLOSSARY. 


245 


On'- pule  (cupula,  a  little  tub}.  The 
m  mma-cup  of  liverworts. 

Cii'  tide  icuticula,  the  skin).  The 
outenno-,1  film  or  pellicle  of  the  epi- 
dermis, differing  chemically  from  the 
remainder  of  the  cell-wall. 

I)«T  ma  -to-gen  (5e'p>Aat  skitt  ;  yetrau, 
/  produce).  The  layer  of  nascent 
epidermis  in  the  meristem  of  growing 
points. 

l>i  ebo  r  o  moiisiSixa,  in  tivo  ;  rinviit, 
1  cut).  Forking  regularly  by  pairs. 

I)i  eot  y-le'd-o-nous  (6is,  double; 
cotyledon).  Having  two  cotyledons, 
or  seed-leaves. 

l)i  le'-cious  (Si's,  double ;  OIKO?,  a 
house).  Having  the  two  sex-organs 
borne  by  distinct  individuals. 

K'l-a  ter  ('Aarjjp,  one  that  expels). 
Spirally  thickened  cells  within  the 
sporogonia  of  some  liverworts,  which 
in  expelling  the  spores. 

K'ni  bry-o  '  t>|3pi>of .  /art us,  or  embryo). 
The  young  plantlet  within  the  seed. 

Embryo-sac.  The  cavity,  within  the 
nucellus,  in  which  the  embryo  de- 
velops. 

Fn  do  de'rm  is  it'i'Soy,  within:  fie'p/^a, 
the  skin).  The  layer  of  cells  inclosing 
th  >  tibro- vascular  bundle  ;  the  bundle 
sheath. 

En  do'g  e  nous  (ei'fiof,  within; 
•yci'i'aw,  I  produced.  Originating  from 
internal  tissues,  and  penetrating  the 
outer  ones. 

K'n  do  sperm  ui-Sor,  within  ;  o-Tre'pjxa, 
the  seed).  A  parenchymatous  tissue 
developed  within  the  embryo-sac. 

K'n  do  spore  leVfioy,  ivithin  ;  spore). 
The  inner  layer  of  a  spore-wall. 

Kn  do  I  hr  <•!  tun  (ev&ov,  ivithin; 
theca).  The  inner  wall  of  the  theca. 

Fp-i-de'rm-is  (en-i,  upon;  Se'pfxa,  the 
skin).  The  outermost  layer  of  special 
cells  covering  plant-surfaces. 

E'p-i-phragm  (ewi,  upon  :  <J>pa-y/ia,  a 
protection}.  In  mosses,  a  membrane 
covering  the  orifice  of  the  capsule. 

Ex  o'g-e  nous  ('efw,  outside :  ytwdu.  I 


produce).      Originating     from    outer 

layers  of  tissue, 
i:  \  ..  -.pore     (tfw,     outside\     spore). 

The  outer  layer  of  a  spore-wall. 
K'x  tine  Dexter,  on  the  outside).     The 

outer  coat  of  a  pollen-spore. 

l-'i  IMT  (fibra,  a  Jiber).  A  long  and 
slender,  thick-walled  cell. 

li    Inous      Composed  of  fibers. 

Fi  bro-va's-cu-lar  (fibra,  a  fiber; 
vasculum,  <t  small  vessel}.  Composed 
of  fibers  and  vessels ;  ffbro-vascular 
bundles  are  the  strands  which  make 
up  the  framework  of  the  higher 
plants. 

Fl'l  a-ment  (filum,  a  thread}.  The 
stalk  of  the  stamen,  supporting  the 
anther ;  also  the  individual  threads  of 
algae  or  fungi. 

Flowering  glume.  In  grasses,  the 
bract  which  subtends  each  flower, 
sometimes  called  lower  palet. 

Frond  (frons,  a  leaf).  A  name  given 
to  the  leaves  of  ferns. 

riiiid:uiirnt:;l  ti»u«-.  That  outside 
the  fibre-vascular  bundles  and  in- 
closed by  the  epidermis,  but  not  in- 
cluded in  either. 

Fu-ni'c-u-lug  (funiculus,  a  slender 
rope}.  The  stalk  of  an  ovule  or  seed. 

Gem'  ma,  pi.  gemmae  (gemma,  a 
bud).  In  bryophytes,  many-celled 
bodies  for  asexual  propagation. 

Glau'-cous  (yAavKos,  pale  green,  fray]. 
Whitened  with  a  bloom,  like  that  on 
a  cabbage-leaf. 

Glume  (gluma,  a  husk).  A  chaff-like 
bract  belonging  to  the  inflorescence 
of  grasses  ;  the  outer  glumes  subtend 
the  spikelet ;  the  flowering  glume  is 
the  bract  of  the  flower. 

Glu'ten  (gluten,  glue}.  A  general 
term  for  the  glue-like  products  of 
plants,  especially  of  seeds. 

Grain.  A  seed-like  fruit,  like  those  of 
grasses,  with  pericarp  adnate  to  the 
seed  ;  also  any  small  rounded  body, 
as  of  starch  or  chlorophyll. 

Growing    point    (punctum    vegeta- 


246 


GLOSSARY. 


tionis).  The  group  of  meristem  cells 
at  the  growing  tip  of  an  organ,  from 
which  the  various  tissues  arise. 
Gy-noe'-ci-um  (yvv>7,  a  female  ;  OIKOS, 
a  house).  The  pistil,  or  collective 
pistils,  of  a  flower. 

Haus-to'-ri-a  (haustor,  a  drinker). 
The  absorbing  organs  of  certain  para- 
sitic plants. 

Her-ma'pli-ro-dite  (ep/u.a<£p6SiTos,  one 
ivko  is  both  male  and  female).  Hav- 
ing both  kinds  of  sexual  organs  borne 
together  on  the  same  axis. 

Host.  The  plant  upon  which  parasitic 
plants  [or  organisms]  develop,  and 
from  which  they  derive  their  nourish- 
ment. 

Hy-gro-sco'p-ic  (uypo?,  ivet ;  o-KOTreto, 
/  look  out  for\.  Having  an  avidity 
for  water. 

Hy-me'n-i-um  (uju.rji',  a  membrane). 
In  fungi,  a  surface  layer  of  vertical 
filaments  containing  or  bearingspores. 

Hy'-pha,  pi.  hyphse  (v(f»j,  a  -web). 
The  slender  vegetative  filaments  of 
fungi  which  may  or  may  not  be 
woven  into  a  mat  (mycelium),  or  a 
plant  body. 

Hy-po-de'r-ma  (UTTO.  under;  Se'p/ixa, 
the  skin).  The  thick-walled  tissues 
beneath  the  epidermis,  which  serve 
to  strengthen  it,  but  do  not  belong 
to  the  fibre-vascular  bundle. 

In-eu'm-bent  (incumbo,  /  lean  upon). 
Leaning  or  resting  upon  ;  of  cotyle- 
dons, when  the  radicle  is  against  the 
back  of  one  ;  of  anthers,  when  they  lie 
against  the  inner  face  of  the  filament. 

In-du'-si-xim,  pi.  indusia  (indusium, 
clothing).  In  ferns,  a  cellular  out- 
growth of  the  leaf  covering  the  clus- 
ters of  sporangia  (sori). 

In-flor  e's-cence  (infloresco,  /  blos- 
som). The  arrangement  of  flowers ; 
or  the  flowering  portion  of  a  plant. 

In  ter-ce'1-lu-lar.  Between  or  among 
the  cells. 

In'-ter-node  (inter,  between  ;  nodus,  a 
joint).  The  part  of  a  stem  between 
two  nodes. 


In'-tine  (inter,  on  the  inside^.  The  in 
ner  coat  of  a  pollen-spore. 

La'm-i-iia  (lamina,  a  layer).  The 
blade,  or  expanded  part,  of  a  leaf. 

Leaf-trace.  The  ribro-vascular  bun- 
dles from  the  leaf  which  descend  into 
the  stem,  and  sooner  or  later  become 
blended  with  its  fibre-vascular  system. 

L,i'g-ule  (ligula,  a  small  tongue).  In 
grasses,  a  thin  appendage  at  the  junc- 
tion of  leaf-blade  and  sheath. 

L,o'd-i-cule  (lodicula,  a  small  cover- 
let). A  small  scale  in  the  flower  of 
grasses. 

Ma'c-ro-spore  (/Aaxpos,  large ;  spore). 
The  larger  spore  of  the  two  kinds 
produced  by  certain  pteridophytes. 

Me'd-ul-la-ry  (medulla,  pith).  Re- 
lating to  the  pith  ;  medullary  rays  are 
the  pith-rays  which  pass  outward 
to  the  bark  between  the  fibro-vascular 
bundles. 

Mer-i's-tem  (juepi^w,  /  divide).  Tis- 
sues in  a  nascent  or  differentiating 
state. 

Me's-o-pliyll  (/ueVos,  middle ;  <£u'AAor. 
a  leaf).  The  green  or  soft  tissue  of 
a  leaf,  supported  by  the  framework 
and  exclusive  of  the  epidermis,  called 
by  the  older  botanists  parenchyma. 

Mi'-cro-pyle  (juiKpos,  small ;  TruArj.  a 
gate).  The  opening  left  by  the  in- 
teguments of  the  ovule,  and  which 
leads  to  the  nucellus. 

Mi'-cro-spore  (/ui/cpos,  small ;  spore). 
The  smaller  spore  of  the  two  kinds 
produced  by  certain  pteridophytes. 

Mi'd  rib.  The  central  or  main  rib  of 
a  leaf  or  thallus. 

Mon  o-po'-di-al  (/adi/os,  single ;  TTOVS, 
a  foot).  Said  of  a  stem  consisting  of 
a  single  and  continuous  axis  (foot- 
stalk). 

My-ce'-li-um  (/U.VKIJS,  a  mushroom; 
At?,  cloth).  The  filamentous  vegeta- 
tive growth  of  fungi,  composed  of 
hyphse. 

Naked.  Wanting  some  usual  cover- 
ing. 


GLOSSARY. 


247 


Ne'e  ta  ry  (nectarium,  a  depository  for 
nectar}.  The  place  or  appendage  in 
which  nectar  is  secreted. 

Nerve  (nervus,  a  nerve).  A  simple 
vein  or  rib. 

Node  (nodus,  a  joint}.  That  part  of  a 
stem  which  normally  bears  leaves. 

Nii-ce'1-lus  (nucella,  a  little  kerne!). 
The  mass  of  the  ovule  within  the  in- 
teguments, sometimes  called  the  nu- 
cleus. 

Nu-rle'-o-lus  (diminutive  of  nucleus). 
The  sharply  defined  point  often  seen 
in  the  nucleus. 

Nu'-cle-us  (nucleus,  a  kernel).  The 
usually  roundish  mass  found  in  the 
protoplasm  of  most  active  cells,  and 
differing  from  the  rest  of  the  proto- 
plasm in  its  greater  density. 

O-o  go'-ni-nm.  pi.  oogouia  tiibr,  /i« 
f£g  •'  y°v*l,  offspring).  The  female  or- 
gan of  oophytes. 

O  o'ph  y-ta  iwor,  an  egg;  <£vrof,  a 
plant).  A  primary  division  of  plants, 
named,  from  the  mode  of  reproduc- 
tion, the  egg-spore  plants.  O'-o-phyte 
is  the  English  equivalent. 

O'-o  sphere  (woy,  an  egg ;  atfralpa,  a 
sphere}.  The  naked  female  egg-cell; 
the  mass  of  protoplasm  prepared  for 
fertilization. 

O'-o-spore  (<ioi>,  an  egg;  spore).  In 
general,  the  egg-cell  after  fertilization, 
and  surrounded  by  a  cell-wall ;  also 
specially  applied  tc  the  spore  formed 
fn  an  oogonium. 

Open  bundle.  A  fibre-vascular  bun- 
dle \vhich  contains  cambium. 

O  pe'r-cu-lum,  pi.  opercula  (oper- 
culum,  a  cover).  In  mosses,  the  ter- 
minal lid  of  the  capsule. 

O'-va-ry  (ovarius,  an  egg-keeper).  That 
part  of  the  pistil  which  contains  the 
ovules. 

O'-vule  (diminutive  of  ovum,  an  egg). 
The  body  which  becomes  a  seed  after 
fertilization. 

Pa  -let  ipalea,  chajff").  In  grasses,  the 
inner  bract  of  the  flower. 

Palisade    cells.      The    elongated 


parenchyma  cells  of  a  leaf,  which 
stand  at  right  angles  to  its  surface, 
and  are  usually  confined  to  the  upper 
part. 

P;i  1-niate  (palma,  the  hand).  Radiat- 
ing like  the  fingers;  said  of  the  veins 
or  divisions  of  some  leaves. 

Pa'n-i-cle  (panicula,  a  tuft).  A  loose 
and  irregularly  branching  flower- 
cluster,  as  in  many  grasses. 

Par-a'ph-y-sis,  pi.  p;ii -;ipli\  •<« •» 
(irapa,  beside ;  <£i>(7is,  nature).  Sterile 
bodies,  usually  hairs,  which  are  found 
mingled  with  the  reproductive  organs 
of  various  cryptogams. 

Pa-re'n  chy  ma  (iropcy^c'w,  I  pour  in 
beside).  Ordinary  or  typical  cellular 
tissue,  i.e.  of  thin-walled,  nearly  iso- 
diametnc  cells. 

Parthenogenesis  ^jrapfln-os.  a. 
virgin;  •yeyecric,  generation).  Com- 
monly applied  to  the  production  of 
seed  without  fertilization  ;  but,  strict- 
ly, the  formation  of  a  sexual  spore 
without  fertilization. 

Pe'd-1  eel  (pediculus,  a  little  foot). 
The  stalk  upon  which  an  organ  is 
borne. 

Pe  du'n-cle  (pedunculus,  a  little  foot}. 
The  general  flower-stalk. 

Pe'r-1-anth  (irepi,  around ' :  ai-0«?,  a 
flouuer).  The  floral  envelopes,  or 
leaves  of  a  flower,  taken  collectively  ; 
and  an  analogous  envelope  of  the 
sporogonia  of  certain  liverworts. 

Pe'r-i-blem  (jrepi'/SArj/xa,  a  covering). 
A  name  given  to  that  part  of  the  mer- 
istem  at  the  growing  point  of  the 
plant-axis,  which  lies  just  beneath  the 
epidermis  and  develops  into  the  cor- 
tex. 

Per-i-ca'm-bi  nin  (irepi,  around ; 
cambium).  In  roots,  the  external 
layer  of  the  fibro-vascular  cylin- 
der. 

Per-i-chae'-ti-um,  pi.  perichaetia 
(Trepi,  around ;  ^ac'r»j,  kair^  or  leaf). 
In  bryophytes,  the  leaves  or  leaf-like 
parts  which  envelop  the  clusters  of 
sex-organs,  forming  in  some  cases  the 
so-called  flower. 


248 


GLOSSARY. 


Pe'r-i-stome  (irepi,  around ;  0To/u.a,  a 
mouth).  In  mosses,  usually  bristle- 
like  or  tooth-like  structures  surround- 
ing the  orifice  of  the  capsule. 

Per-i  the'  ci-um,  pi.  perithecia 
(wept,  around ;  0»JKtj,  a-  case).  The 
spore-vessel  of  certain  carpophytes, 
containing  the  spore-sacs  (asci). 

Pe't-al  (Tre'raAoi',  a  leaf).  A  corolla 
leaf. 

Pe't-i-ole  (petiolus,  a  little  f oof).  The 
stalk  of  a  leaf. 

Phan-e-ro-ga'-mi-a  (<J>af  epos,  evident  ; 
yajw,os,  marriage).  A  primary  division 
(the  highest)  of  plants,  named  from 
their  mode  of  reproduction,  the  seed- 
producing  plants.  Pha' n-e-ro-gam  is 
the  English  equivalent. 

Phlo'-em  (</>Aot6s,  the  inner  bark). 
The  bark  or  bast  portion  of  a  fibre- 
vascular  bundle. 

Phy-co-cy'-aii-ine  (^UKOS,  sea-weed; 
KUO.I/OS,  dark  blue).  A  bluish  coloring 
matter  extracted  by  water  from  cer- 
tain algae. 

Phy'1-lo-tax-y  (</>vAAov,  a  lea/;  rafi?, 
arrangement).  Leaf -arrangement. 

Pi'n-na,  pi.  pinnae  (pinna,  a  feather). 
One  of  the  primary  divisions  of  a 
pinnate  leaf,  as  in  ferns. 

Pi'n-nule  (pinnula,  a  little  feather). 
One  of  the  divisions  of  a  pinna. 

Pi's-til  (pistillum,  a  pestle).  The  fe- 
male organ  in  phanerogams. 

Pit.  A  thin  place,  or  pit-like  depres- 
sion, left  in  the  thickening  of  a  cell- 
walk 

Pla-ce'n-ta,  pi.  placentae  (placenta, 
a  cake).  That  portion  of  the  ovary 
which  bears  the  ovules. 

Ple'-rome  (TrArjpw/aa,  that  which  fills). 
A  name  given  to  that  part  of  the  mer- 
istem  near  the  growing  points  of  the 
plant-axis,  which  forms  a  central  shaft 
or  cylinder  and  develops  into  the 
axial  tissues. 

Plu'-mule  (plumula,  a  small,  soft 
feather).  The  terminal  bud  of  the 
embryo  above  the  cotyledons. 

Pod.  A  dry,  several-seeded,  dehiscent 
fruit;  or  a  similar  spore-case. 


Po'l-len  (pollen,  fine  flour).  The 
spores  developed  in  the  anther. 

Pol-lin-a'-tion.  The  transfer  of  pol- 
len to  its  stigma. 

Pro-einbryo  (pro,  before;  embryo). 
In  phanerogams,  the  chain  of  cells 
(suspensor)  formed  after  fertilization, 
and  from  the  lower  end  of  which  the 
embryo  develops. 

Pro-tha'1-li -uin,  pi.  prothallia(pro, 
before ;  thallus,  a  young-  shoot).  In 
pteridophytes,  the  small  usually 
short-lived  plant  which  develops  from 
the  spore,  and  bears  the  sex-organs. 

Pro-to-ne'-ma,  pi.  protone'inata 
(TrpuiTo?,  first ;  JJjota.,  that  ivhick  is  sent 
out).  In  mosses,  the  filamentous, 
growth  which  is  produced  by  the 
spores,  and  from  which  the  leafy 
moss  plant  is  developed. 

Pro-to'pli-y-ta  (TTPUJTOS,  the  first; 
<f>vTov,  a  plant).  A  primary  division 
of  plants,  named  from  the  fact  that 
they  include  the  lowest  known  plants. 
Pro'-to-phyte\?,  the  English  equivalent 

Pro'-to  plasm  (7rpo>Tos,  first ;  7rAot<r/u.a, 
that  which  has  been  formed).  That 
substance  in  living  cells,  of  varying 
consistency,  which  is  the  seat  of  all 
vital  phenomena. 

Pte'r-i-doid  (n-Tepis,  a  fern;  elfios, 
form).  Fern  like. 

Pter-i-do'pll-y-ta  (irrepts,  a  fern; 
</>uTOf,  a  plant).  A  primary  division 
of  plants,  named  from  its  principal 
group,  the  ferns.  Pte-ri' d-o-pJiyte  is 
the  English  equivalent. 

Py'r-e-noid  (irvp^v,  kernel;  eiSos. 
form).  Minute  colorless  bodies  im- 
bedded in  the  chlorophyll  structures 
of  some  lower  plants. 

lla'pli-i-de*  (pat/us,  a  needle;  etfios, 
form).  Needle-like  plant-crystals. 

Ke-ce'p  ta-cle  (receptaculum,  a  recep- 
tacle). That  portion  of  an  axis  or 
pedicel  (usually  broadened)  which 
forms  a  common  support  for  a  cluster 
of  organs,  in  most  cases  sex-organs. 

Ke-ti'c-u-la-ted  (reticulatus,  net-like). 
Having  a  net-like  appearance. 


GLOSSARY. 


249 


Rha'-chig  (pixi?,  the  backbone}.  The 
axis  of  a  compound  leaf,  or  of  a  spike. 

Kha'-phe  (pa^>^,  a  stunt).  In  an  anat- 
ropous  ovule,  the  ridge  which  con- 
nects the  chala/a  with  the  hilum. 

Khi  /oitl  (p'i'£a.  a  root ;  elfios,  form). 
Root-like  ;  a  name  applied  to  the  root- 
like  hairs  found  in  bryophytes  and 
pteridophytes. 

Rhi'-zo-tax-y  ip'i£a,  a  root;  rafts,  ar- 
rangement).  Root-arrangement. 

Roo't  stock.  A  horizontal,  more  or 
less  thickened,  root  like  stem,  either 
on  the  ground  or  underground. 

Sca-la'r-i-form  (scalaria,  a  ladder; 
forma,  form}.  A  name  applied  to 
ducts  with  pits  horizontally  elongated 
and  so  placed  that  the  intervening 
thickening  ridges  appear  like  the 
rounds  of  a  ladder. 

Scale  (scala,  a  Jliglit  of  steps).  Any 
thin  scarious  body,  as  a  degenerated 
leaf,  or  flat  trichome. 

Scle-re'ii  chy-ma  (o-KA^po?,  hard: 
tyxvua,  an  infusion).  A  tissue  be- 
longing to  the  fundamental  system 
and  composed  of  cells  that  are  thick- 
walled,  often  excessively  so. 

Sen  te'l-lum  (scutella,  a  small  disk)- 
The  disk-like  or  shield-like  cotyledon 
of  grasses. 

Seed.  The  fertilized  and  matured 
ovule. 

Se'p  al  (from  the  modernized  word 
o-eVaAoi',  a  sepal).  A  calyx  leaf. 

Se'-ta,  pi.  setae  (seta,  a  bristle).  A 
bristle,  or  bristle-shaped  body ;  in 
mosses,  the  stalk  of  the  capsule. 

Sheath.  A  thin  enveloping  part,  as  of 
a  filament,  leaf,  or  resin-duct. 

Sieve-cells.  Cells  belonging  to  the 
phloem,  and  characterized  by  the  pres- 
ence of  circumscribed  and  perforated 
panels  in  the  walls ;  the  panels  are 
sieve-plates,  and  the  perforations 
sieve-pores. 

So'-rus,  pi.  sorl  (o-topo?,  a  heap}.  In 
ferns,  the  groups  of  sporangia,  con- 
stituting the  so-called  "  fruit-dots  ;  " 
in  parasitic  fungi,  well-defined  groups 


of  spores,  breaking  through  the  epi- 
dermis of  the  host. 

Spike  (spica,  an  ear  of  corn).  A  flower- 
cluster,  having  its  flowers  sessile  on 
an  elongated  axis. 

Spi'ke-let  (diminutive  of  spike).  A 
secondary  spike  ;  in  grasses,  the  ulti- 
mate flower-cluster,  consisting  of  one 
or  more  flowers  subtended  by  a  com- 
mon pair  of  glumes. 

Spo-ra'n-gi-um,  pi.  sporangia 
(spore ;  ayyos,  a  vessel).  The  spore- 
vessel  ;  applied  to  ferns  and  certain 
lower  groups. 

Spore  (<r7ropa,  seed).  Originally  used 
as  the  analogue  of  seed  in  flowerless 
plants  -,  now  applied  to  any  one-celled 
or  few-celled  body  which  is  separated 
from  the  parent  for  the  purpose  of 
reproduction,  whether  sexually  or 
asexually  produced  ;  the  different 
methods  of  its  production  are  indi- 
cated by  suitable  prefixes. 

Spo-ro  go'-ni-um,  pi.  sporogonia 
(spore ;  yoyjj,  offspring).  The  whole 
structure  of  the  spore-bearing  stage 
of  bryophytes. 

Sta'-meil  (arr^w,  the  -warp  or  thread 
of  cloth).  The  male  organ  in  phane- 
rogams. 

Sti'g-ma  (o-riy/uia,  a  spot,  or  mark). 
The  surface  of  a  pistil  without  epi- 
dermis which  receives  the  pollen. 

Stig-ma't-ic.  Relating  to  the  stigma, 
or  stigma-like. 

Sto'-ma,  pi.  sto'mata  (orojbta,  a 
mouth).  Epidermal  structures  which 
serve  for  facilitating  gaseous  inter- 
changes with  the  external  air,  often 
called  "breathing-pores." 

Stro'-phi-ole  (strophiolum,  a  small 
•wreath).  An  appendage  at  the  hilum 
of  certain  seeds. 

Style  (oriJAos,  a  pillar}.  The  usually 
attenuated  portion  of  the  pistil  which 
bears  the  stigma. 

Sus-pe'n-sor  (suspendo,  /  hang).  See 
Pro-embryo. 

Syn-e'r-gi  dae,  or  Synergides 
(o-vi'epyeto,  /  ivork  together).  The  two 
nucleated  bodies  which  accompany 


250 


GLOSSARY. 


the  oosphere  in  the  embryo-sac,  and 
together  with  it  form  the  egg-appara- 
tus. 

Te's-ta  (testa,  a  shell).  The  outer 
seed-coat. 

T«t-ra-dy'n-a-inous  (Terpas,  four; 
SuVa/oas,  strength}.  Said  of  an  andrce- 
cium  in  which  there  are  four  long  and 
two  shorter  stamens. 

Tha'1-loid  (thallus ;  elfios,  form). 
Thallus-like. 

Tha'1-lus  (0aAA.6?,  a  young  shoot). 
The  body  of  lower  plants,  which  ex- 
hibits no  differentiation  of  stem,  leaf, 
and  root. 

The'  ca,  pi.  thecae  (0rJKTj,  a  case).  The 
"anther-cell,"  that  is,  the  case  con- 
taining pollen ;  sometimes  used  of 
other  spore-cases. 

Tra'cheary  tissue.  A  general  name 
given  to  the  yessels  and  ducts  found 
in  fibro  vascular  bundles. 

Tra'-che-ides  (rpa^vs,  rough;  elSos, 
form).  Tracheary  cells  that  are  closed 
throughout. 

Tri'-chome  (0pt£,  hair).  A  general 
name  for  a  slender  outgrowth  from 
the  epidermis,  usually  arising  from  a 
single  cell. 


Tur-gi'd  i  ty  (turgidus,  swollen*).  The 
normal  swollen  condition  of  cells 
which  results  from  the  avidity  of  pro- 
toplasm for  water. 

Vein  (vena,  a  vein).  The  fibre-vascu- 
lar bundle  of  leaves  or  any  flat  organ. 

Ve  na'-tion  (vena,  a  vein).  The  mode 
of  vein  distribution. 

Xy'-lem  (f  JA.oi',  wood).  The  wood 
(inner)  portion  of  the  fibre-vascular 
bundle. 

Zo'-o-spore  (£Aov,  an  animal ;  spore). 
A  free-moving  spore. 

Zy-go-mo'r-phic  (£vyov,  a  yoke: 
Mop<J»7,  form).  Said  of  a  flower  which 
can  be  bisected  by  only  one  plane  into 
similar  halves. 

Zy-go'ph-y-ta  (£vyov,  a  yoke  ;  $VTOV,  a 
plant).  A  primary  division  of  plants, 
named  from  their  mode  of  reproduc- 
tion, the  sexual  spore  being  produced 
by  conjugation.  Zy'-go-phyte  is  the 
English  equivalent. 

Zy'-go-spore  (fryov,  a  yoke:  spore). 
The  spore  of  zygophytes,  formed  by 
conjugation. 


INDEX 


Numbers  in  light  type  refer  to  the  laboratory  part,  those  in  heavy 
type  to  other  parts  of  the  book. 


ALTERNATION  of  generations,  100 

Acliantum,  means  of  recognizing, 
103;  gross  anatomy,  105;  mi- 
nute anatomy,  in;  annotations, 
124 

Anatropous  ovule,  214,  217 

Androecium,  202 

Annual  rings,  162 

Annulus,  no,  120 

Anther,  178,  189,  203,  226 

Antheridia,  47,  48,  55,  63,  72,  82, 
88,  93,  122,  128,  168 

Antherozoids,  63,  72,  82,  93,  100, 
122,  128,  169 

Anthotaxy,  176 

Antipodal  cells,  241 

Apical  cell,  nS 

Apophysis,  89,  96 

Appendages  of  perithecia,  54,  57 

Archegonia,  75,  77,  82,  88,  94,123, 
129,  161,  168 

Areolae,  60 

Asci,  54 

Ascospores,  54 

Atrichum,  how  to  recognize,  84; 
gross  anatomy.  86;  minute 
anatomy,  90;  annotations,  97; 


discovery  of  the  sexual  organs, 
99;  nature  of  the  fruit,  100 

Avena,  gross  anatomy,  172;  mi 
nute anatomy,  i8o;annotations, 
192;  homology  of  the  flower,  193 

Awn,  177 

Axis  of  inflorescence,  176 

BARK,  136 

Bast  parenchyma,  209 

Blade  of  leaf,  175 

Books  of  reference,  20 

Bordered  pits,  144,  147,  164 

Bracts,  139,  162,  193,  237 

Branches,  arrangement  of,  133 

Bulliform  cells,  195 

Bundle  sheath,  in,  113,  126,  153. 

155,    181,   184,    206,   219,    229, 

231,  240 

CALLUS-PLATE,  165 
Calyptra,  86,  89,  97,  101 
Calyx,  202 

Cambium,  142,  144,  147,  164,  239 
Camel's-hair  brush,  how  mount- 
ed, 3 
Camera  lucida,  use  of.  19 


252 


INDEX. 


Campylotropous  seed,  227 
Canal  of  archegonia,  77,  94,  123, 

129 
Capsella,  how  to  recognize,  222; 

gross    anatomy,    223;     minute 

anatomy,  228;  annotations,  236 
Capsule,  86,  89,  95,  101 
Carpellary  scale,   139,    M°»    ^Q. 

163 

Carpels,  163,  202,  204,  213,  217 
Carpogonium,  55 
Carpophyll,  163 
Carpophyta,  48,  55 
Caryopsis,  179 

Caulicle,  141,  180,  192,  228,  236 
Cell,  25;  division  of  the,  26 
Cell-sap,  40 
Cellulose,  26 
Cell-wall,  24,  26 
Chaff  of  moss,  88;  of  oats,  179 
Chalaza,  205 
Chlor-iodide  of  zinc,  5 
Chlorophyll,  test  for,  23,  29,  31; 

nature  of,   25;   bands,   36,    40; 

bodies,  24,  77,  119  ;  grains,  67, 

77 

Cilia,  26,  47,  73,  83,  94,  100,  123 
Closed  bundle,  195,  209,  220 
Collateral  bundle,  165,  195,  240 
Columella,  90,  95 
Concentric  bundle,  114,  126 
Conducting  tissue  of  style,   221, 

241 

Cones,  140,  159 
Conidia,  44,  45,  50,  53,  56 
Conidiophores,  45,  46,  53 
Conjugating  filaments,  35;  tubes, 

38 
Connective  of   anther,   189,  203, 

212 
Conocephalus,  59,  61 


Continuity  of  protoplasm,  127 

Cork,  229 

Corolla,  202 

Corpuscula,  161 

Cotyledons,  141,  180,  228,  236 

Cover-glasses,  cleaning,  11;  kind 

to  use,  3;  receptacle  for,  11 
Cupules,  60,  62,  68 
Cuticle,  112,  146,  152,  183 
Cystopus,  where  found,  43;  gross 
anatomy,  44;  minute  anatomy, 
45;  annotations,   48;    mode  of 
life,  49;  means  of  distribution, 
49;  nature  of  its  parasitism,  50 

DARK-GREEN  scum,  28 
Definitive  nucleus,  241 
Dermatogen,  182,  206 
Dichotomous  branching,  60,  79 
Dicotyledons,  characters  of,  236 
Dispersion  of  offspring,   50,   170 
Drawing,  importance  of,  16;  kinds 

of,   17,    18;   suitable    materials 

for,  4 

ELATERS,  65,  76,  83 

Embryo,  141,  170,  179.  192,  205, 

215,  228,  235 
Embryonal  vesicle,  241 
Embryo-sac,  140,    160,   169,  214, 

235,  241 

Empty  glume,  176 
Endogenous  origin  of  roots,  192. 

208,  220 
Endosperm,    140,    141,    160,  169, 

178,  241 
Endospore,  121 
Endothecium,  189,  213,  234 
Epidermis,  66,  91,   112,  118,   152, 

154,  157,  181,  183,  186,  188,  211, 

230 


INDEX. 


253 


.Epiphragm,  89,  96,  101 
Exogenous  growth,  208,  220 
Exospore,  121 
Extine>  158,  RJO.  213,  234 

FERTILIZATION,  mode  of  contact 

in,  169;  in  Finns,  170 
Fertilizing-tube,  48,  49,  51,  169 
Fibrous  tissue,  120 
Fibro-vascular  bundle,  113,    125. 

153,  166,  181,  184,  209,  229,  230 
Filament  of  stamen,  178,  203,  212, 

226.  233 

Flowering  glume,  177,  193 
Flower,  character  of  a  true,  216; 

in  Pinus,  162;  nature  of,  in  oats, 

193 

Forceps,  3 
Frond,  105 
Funiculus,  205,  214,  227 

GEM.M.E.  60,  62.  70.  80 
Germination  of    conidia,   56;   of 

moss  spores,  102 
Glume,  176,  177,  188,  193 
Gluten-containing  cells,  191 
Glycerine,  6,  13 
Grain  of  oats,  179,  195 
Green  slime,  22 
Growing.point,  151,  182,  195,  200, 

208,  219 

Growth  rings,   135,   142,  162.  165 
Guard-cells,  66,  118,  152,166,  183, 

1 86 
Gyncecium,  202 

HAIRS  of  thallus,  60,  61,  78;  of 
Cjpule,  69;  of  fruit,  179 

Haustofia,  46,  49,  53,  56 

Head  of  liverwort,  63,  64,  81;  of 
moss,  86,  87,  93 


Hermaphrodite  flower,  194 

Hygroscopic  cells,   176,   187,  195 

Hymenium,  45 

Hyphae,  46 

Hypoderma,  152,  154,  183 

INWSIUM,  no 

Instruments  for  laboratory,  1 

Integument   of   ovule,    139,    159, 

163,  235 

Intercellular  spaces,  127,  185,  209 
Iniernodes,  105,  174,  199 
Inline,  158,  170,  190,  213,  234 
Iodine,  5 

KEEL  of  carpellary  scale,  139,  164 

LAMINA,  87,  92 

Leaf-trace,  91,  99,  219 

Leaves  of  Marchantia,  61,  68,79; 
of  Atrichum,  87.  92  98;  of 
Adiantum  107,  118;  of  Pinus, 
137.  151,  162;  of  Avena,  175;  of 
Trillium,  220;  of  Capsella,  225 

Ligule,  175,  193 

Lilac  mildew,  52 

Liverwort,  58 

Lodicules,  177,  193 

Lunularia,  59 

MACROSPORES,  168,  241 

Magenta,  5 

Magnifying  power  of  micro- 
scope, 18 

Maiden-hair  fern,  104 

Marchantia,  how  to  recognize. 
58;  gross  anatomy,  59;  minute 
anatomy  66;  annotations,  77 

Material,  care  and  use  of,  15 

Medullary  rays,  135,  142,  145,  240 

Meristem,  151,  206,  228 


254 


INDEX. 


Mesophyll,  109,  119,  138,  153, 
155,  166,  175,  187,  210,  232 

Microscope,  use  of,  6;  fine  ad- 
justment, 16;  high  and  low  pow- 
ers, 3;  to  determine  magnifying 
power,  18 

Microsphaera,  how  to  recognize, 
52;  gross  anatomy,  52;  minute 
anatomy,  53;  annotations,  55 

Microspores,  168,  240 

Micropyle,  139,  140,  159 

Middle  lamella,  112,  127,  144,  207 

Midrib  of  thallus,  60;  of  leaf,  87, 
92,  99 

Moss,  84 

Mounting,  11 

Movements  of  Oscillaria,  32 

Mycelium,  45,  53 

NAKED  ovule  in  Pinus,  163 

Nectaries,  226 

Needles  for  dissecting,  2 

Nerves,  176 

Nodes,  105,  174,  192,  199 

Nucellus,  140,  159,  214 

Nucleolus,  24.  38 

Nucleus,  24,  25,  37;  of  starch,  112 

Nutritive  solution,  34 

OATS,  172 

Oogonia,  47,  48 

Oophyta,  48 

Oosphere,    47,    77,    83,   94,    100, 

124,  129,  170,  241 
Oospore,  44,  48,  49,  235,  242 
Open  bundle,  240 
Operculum,  89,  96 
Oscillaria,     occurrence     of,     28; 

gross  and  minute  anatomy,  29; 

annotations,  31;  movements  of, 

32 


Ovary,  178,   195.   203,    214.   221, 

234,  238 
Ovules,   139,   140,   162,   178,  194, 

204,  214,  217,  235 

PALET,  177,  188,  193 

Palisade    parenchyma,   187,    210, 

232 

Panicle,  176 

Paraphyses,  72,  75,  82,  88,  93 
Parenchyma,    67,    70,    113,     142, 

143,  145,  153,  183,  187,  209 
Parthenogenesis,  51,  55 
Pedicel  of  receptacle,  60,  62,  70, 

73,  81;  of  gemma,  70;  of  flower. 

223,    237;    of    conidia,    45;    of 

archegonia,  94;  of  asci,   54;  of 

antheridia,  72,  93 
Peduncle,  139 
Pencils  for  drawing,  4 
Pens  for  drawing,  4 
Perianth,  65,  76.  194,  216 
Periblem,  182,  206 
Pericambium,  117,  126,  207 
Perichaetium,  64,  75,  82 
Peristome,  89,  96 
Perithecia,  53,  54 
Petals,  202,  212,  226,  233,  238 
Petiole,  201 

Phloem,  113,  142,  144,  153,  209 
Phycocyanine,  29,  31 
Phyllotaxy,  225 
Pinnae,  108 
Pinnules,  107,  108 
Pistil,  178,  227,  234 
Pith,    135,   142,  231;   for   section 

cutting,  10 
Pits   in  cell-wall,   112,   127,  144, 

147,  152 

Placentae,  204,  217 
Plerome,  182,  206 


INDEX. 


255 


Plumule,  141,  180,  192 

Pod,  205 

Pollen,   138,   158,  169,   178,    189, 

190,  194,  203,  213,  227,  234 
Pollen  sac,  138,  157,  194 
Pollen  tube,  169,  235,  241 
Pollination  in  Pinus,  164 
Polytrichum    85 
Pond  scum,  33 
Potassic  chlorate,  6;  hydrate,  5, 

13 

Primary  meristem,  151,  206 
Primordial  utricle,  40 
Pro  embryo,  235,  242 
Prothallia,     104,    in,    121,    128, 

168,  194,  241 
Protococcus,  distribution  of,  22; 

gross  and  minute  anatomy,  23; 

annotations,  25 
Protonema,  86,  90,  102 
Protoplasm,   test  for,   24,  25;  in 

the  cell,  40;  in  pollen,  158 
Pteridoid  stage,  128 
Punctum  vegetationis,  219 
Pyrenoid,  37,  40 

RADIAL  bundle,  117,  126, 195,  218 

Radish  flowers,  43 

Raphides,  201,  233 

Razor,  kind  to  use,  2;  care  of,  9 

Reagents,  4;  use  of ,  13 

Receptacle,  60,    64,   71,    74,    87, 

202,  226 

Reference  books,  19 
Resin-ducts,    135,   143,    145,    148 

153,  155,  167 

Resting  spores,  42,  49,  56 
Rhachis  of  leaf,  107;  of  spikelet, 

177 

Rhaphe,  205 
Rhizoids,  61,  79,  86,  90,  in,  i?2 


Rhizome,  105 

Rhizotaxy,  223 

Roots,-  79,    105,    116,    124,    173, 

219,  238 
Root  cap,  107,  118,  124,  174,  182, 

205,  238 

Root-hairs,  97,  107,  118,  174,  206 
Root-sheath,  180,  192 
Root-stock,  198,  199,  207,  218 

SCALARIFORM     VCSSels,     133,     JI4, 

"7 

Scale  leaves  of  Atrichum,  87;  of 
Pinus,  132,  137,  146,  149,  lefc; 
of  Trillium,  200,  201,  218 

Scales  (trichomes)  on  rhizome, 
105,  107.  116;  on  thallus,  60, 
62,  79 

Sclerenchyma,  in,  115 

Scotch  pine,  130 

Scutellum,  180,  192 

Section  cutting,  8 

Seed,  141,  170.  205,  215,  227,  236 

Selaginella,  168 

Sepals,  202,  2ii,  226,  233 

Seta,  86,  89,  95,  100 

Sexuality,  simplest  form  of,  42; 
significance  of,  51 

Sexual  process,  41 

Sheath  of  filament,  30,  31,  36,  39; 
of  leaf,  175,  188;  of  resin  duct, 
143;  of  root,  1 80.  192;  of  root- 
stock,  208,  220;  of  bundle — see 
Bundle  sheath 

Shepherd's-purse,  222 

Sieve  cells,  113,  115,  144,  148, 
165;  plates,  115,  126,  145,  165; 
tissue,  207,  209 

Sori,  44,  no 

Sperm-cell,  122 

Spike,  139 


256 


INDEX. 


Spikelet,  176 

Spiral  vessels,  143,  225 

Spirogyra,  occurrence  of»  33;  to 
grow,  34;  gross  anatomy,  34; 
minute  anatomy,  35;  annota- 
tions, 39 

Spongy  parenchyma,  210,  221, 
232 

Sporangia,  no,  120 

Sporogonia,  64,  76,  83,  86,  no, 
120 

Staining,  13 

Stamens,  132,  138,  157,  162,  178, 
194,  202,  212,  226,  233,  238 

Starch,  37,  40,  112,  158 

Stigmas,  178,  190,  194,  204,  217, 
234 

Stigmatic  cells,  77,  83,  94;  sur- 
faces, 213 

Stomata,  61,  66,  68,  71,  78,  101, 
119,  127,  138,  152,  188 

Strophiole,  205,  215 

Styles,  178,  190,  204,  217 

Subterranean  stem,  199 

Sulphuric  acid,  6,  13 

Supplementary  guard-cells,  66 

Suspensor,  242 

Synergidse,  241 

TAP  root,  237 

Teeth  of  the  peristome,  97,  101 

Testa,  205,  215,  236 


Tetradynamous  stamens,  237 
Thalloid  stem,  77,  128 
Thallus,  59,  66,  77 
Thecse  of  anther,  189,  203,  2J2, 

234 

Tillering  point,  173 
Tracheides,  143,  147,  164,  167,  182 
Transfusion  tissue,  167 
Trichomes,  61,  66,  75,   105^,  120, 

122,  125,  173,  191 
Trillium,      description     of,     197; 

gross    anatomy,     198;    minute 

anatomy,  205;  annotations,  215 
Turgidity  of  cells,  30,  32,  38 

VEINS,  109,  201,  2ii 
Venation,  109,  218 
Vesicle  of  antherozoid,  73,  83,  94, 
123 

WHITE  rust,  43 

Wings  of  thallus,  60;  of  pollen, 

158 
Wood,   135,   142,  164;  cells,  143; 

parenchyma,  209 

XYLEM,   113,  142,  143,  147,  153, 
209 

ZOOSPORES,  26,  47,  50 
Zygophyta,  48 
Zygospores,  35,  39,  42 


THE  AMERICAN  SCIENCE  SERIES. 


The  principal  objects  of  the  series  are  to  supply  the  lack — in 
some  subjects  very  great— of  authoritative  books  whose  princi- 
ples are,  so  far  as  practicable,  illustrated  by  familiar  American 
facts,  and  also  to  supply  the  other  lack  that  the  advance  of  Sci- 
ence perennially  creates,  of  text-books  which  at  least  do  not 
contradict  the  latest  generalizations.  The  scheme  systemati- 
cally outlines  the  field  of  Science,  as  the  term  is  usually  em- 
ployed with  reference  to  general  education,  and  includes 
ADVANCED  COURSES  for  maturer  college  students,  BRIEFER 
Cor  USES  for  beginners  in  school  or  college,  and  ELEMENTARY 
COURSES  for  the  youngest  classes.  The  Briefer  Courses  are  not 
mere  abridgments  of  the  larger  works,  but,  with  perhaps  a 
single  exception,  are  much  less  technical  in  style  and  more 
elementary  in  method.  While  somewhat  narrower  in  range 
of  topics,  they  give  equal  emphasis  to  controlling  principles. 
The  following  books  in  this  series  are  already  published: 

THE  HUMAN    BODY.     BY  H.  NEWELL  MARTIN,  Professor  in 

the  Johns  Hopkins  University. 
Advanced  Course.     Large  I2mo.     Pp.  655.     $2  75. 

Designed  to  impart  the  kind  and  amount  of  knowledge  every 
educated  person  should  possess  of  the  structure  and  activities 
and  the  conditions  of  healthy  working  of  the  human  body. 
While  intelligible  to  the  general  reader,  it  is  accurate  and  suffi- 
ciently minute  in  details  to  meet  the  requirements  of  students 
who  are  not  making  human  anatomy  and  physiology  subjects  of 
special  advanced  study.  The  regular  editions  of  the  book  contain 
an  appendix  on  Reproduction  and  Development.  Copies  without 
tht<  will  be  sent  when  specially  ordered. 

From  the  CHICAGO  TRIBUNE:  "  The  reader  who  follows  him  through 
to  the  end  of  the  book  will  be  better  informed  on  the  subject  of 
ir.odern  physiology  in  its  general  features  than  most  of  the  medical 
practitioners  who  rest  on  the  knowledge  gained  in  comparatively  an- 
tiquated text-books,  and  will,  if  possessed  of  average  good  judgment 
and  powers  of  discrimination,  not  be  in  any  way  confused  by  state- 
ments of  dubious  questions  or  conflicting  views." 


2  THE  AMERICAN  SCIENCE   SERIES. 

THE  HUMAN  BODY— Continued. 
Briefer  Course.     12010.     Pp.  364.     $1.50. 

Aims  to  make  the  study  of  this  branch  of  Natural  Science  a 
source  of  discipline  to  the  observing  and  reasoning  faculties, 
and  not  merely  to  present  a  set  of  facts,  useful  to  know,  which 
the  pupil  is  to  learn  by  heart,  like  the  multiplication-table. 
With  this  in  view,  the  author  attempts  to  exhibit,  so  far  as  is 
practicable  in  an  elementary  treatise,  the  ascertained  facts  of 
Physiology  as  illustrations  of,  or  deductions  from,  the  two  car- 
dinal principles  by  which  it,  as  a  department  of  modern  science, 
is  controlled, — namely,  the  doctrine  of  the  "Conservation  of 
Energy"  and  that  of  the  "  Physiological  Division  of  Labor."  To 
the  same  end  he  also  gives  simple,  practical  directions  to  assist 
the  teacher  in  demonstrating  to  the  class  the  fundamental  facts 
of  the  science.  The  book  includes  a  chapter  on  the  action  upon 
the  body  of  stimulants  and  narcoiics. 

From  HENRY  SEWALL,  Professor  of  Physiology,  University  of  Michi- 
gan :  "  The  number  of  poor  books  meant  to  serve  the  purpose  of 
text-books  of  physiology  for  schools  is  so  great  that  it  is  well  to 
define  clearly  the  needs  of  such  a  work  :  I.  That  it  shall  contain  ac- 
curate statements  of  fact.  2.  That  its  facts  shall  not  be  too  numer- 
ous, but  chosen  so  that  the  important  truths  are  recognized  in  their 
true  relation.  3.  That  the  language  shall  be  so  lucid  as  to  give  no 
excuse  for  misunderstanding.  4.  That  the  value  of  the  study  as  a 
discipline  to  the  reasoning  faculties  shall  be  continually  kept  in  view. 
I  know  of  no  elementary  text-book  which  is  the  superior,  if  the 
equal,  of  Prof.  Martin's,  as  judged  by  these  conditions." 

Elementary  Course.     I2mo.     Pp.  261.     90  cts. 

A  very  earnest  attempt  to  present  the  subject  so  that  children 
may  easily  understand  it,  and,  whenever  possible,  to  start  with 
familiar  facts  and  gradually  to  lead  up  to  less  obvious  ones. 
The  action  on  the  body  of  stimulants  and  narcotics  is  fully  treated. 

From  W.  S.  PERRY,  Superintendent  of  Schools,  Ann  Arbor,  Mich.  : 
"  I  find  in  it  the  same  accuracy  of  statement  and  scholarly  strength 
that  characterize  both  the  larger  editions.  The  large  relative  space 
given  to  hygiene  is  fully  in  accord  with  the  latest  educational  opinion 
and  practice  ;  while  the  amount  of  anatomy  and  physiology  comprised 
in  the  compact  treatment  of  these  divisions  is  quite  enough  for  the 
most  practical  knowledge  of  the  subject.  The  handling  of  alcohol 
and  narcotics  is,  in  my  opinion,  especially  good.  The  most  admira- 
ble feature  of  the  book  is  its  fine  adaptation  to  the  capacity  of  younger 
pupils.  The  diction  is  simple  and  pure,  the  style  clear  and  direct,  and 
the  manner  of  presentation  bright  and  attractive." 


THE  AMERICAN  SCIENCE   SERIES.  3 

ASTRONOMY.  BY  SIMON  NEWCOMB,  Professor  in  the  Johns 
Hopkins  University,  and  EDWARD  S.  HOLDEN,  Director  of 
the  Lick  Observatory. 

Advanced  Course.     Large  12  mo.     Pp.  512.     $2.50. 

To  facilitate  its  use  by  students  of  different  grades,  the  sub- 
ject-matter is  divided  into  two  classes,  distinguished  by  the  size 
of  the  type.  The  portions  in  large  type  form  a  complete  course 
for  the  use  of  those  who  desire  only  such  a  general  knowledge 
of  the  subject  as  can  be  acquired  without  the  application  of  ad- 
vanced mathematics.  The  portions  in  small  type  comprise  ad- 
ditions for  the  use  of  those  students  who  either  desire  a  more 
detailed  and  precise  knowledge  of  the  subject,  or  who  intend  to 
make  astronomy  a  special  study. 

From  C.  A.  YOUNG,  Professor  in  Princeton  College:  "  I  conclude 
that  it  is  decidedly  superior  to  anything  else  in  the  market  on  the 
same  subject  and  designed  for  the  same  purpose." 

Briefer  Course.     I2mo.     Pp.  352.     $1.40. 

Aims  to  furnish  a  tolerably  complete  outline  of  the  as- 
tronomy of  to-day,  in  as  elementary  a  shape  as  will  yield  satis- 
factory returns  for  the  learner's  time  and  labor.  It  has  been 
abridged  from  the  larger  work,  not  by  compressing  the  same 
matter  into  less  space,  but  by  omitting  the  details  of  practical 
astronomy,  thus  giving  to  the  descriptive  portions  a  greater 
relative  prominence. 

From  THE  CRITIC:  "The  book  is  in  refreshing  contrast  to  the 
productions  of  the  professional  schoolbook-makers,  who,  having  only 
a  superficial  knowledge  of  the  matter  in  hand,  gather  their  material, 
without  sense  or  discrimination,  from  all  sorts  of  authorities,  and 
present  as  the  result  an  indigesta  moles,  a  mass  of  crudities,  not  un- 
mixed with  errors.  The  student  of  this  book  may  feel  secure  as  to 
the  correctness  of  whatever  he  finds  in  it  Facts  appear  as  facts,  and 
theories  and  speculations  stand  for  what  they  are,  and  are  worth." 

From  W.  B.  GRAVES,  Master  Scientific  Department  of  Phillips 
Academy:  "  I  have  used  the  Briefer  Course  of  Astronomy  during  the 
past  year.  It  is  up  to  the  times,  the  points  are  put  in  a  way  to  inter- 
est the  student,  and  the  size  of  the  book  makes  it  easy  to  go  over  the 
subject  in  the  time  allotted  by  our  schedule." 

From  HENRY  LEFAVOUR,  late  Teacher  of  Astronomy,  Williston  Semi- 
nary :  "The  impression  which  I  formed  upon  first  examination,  that 
it  was  in  very  many  respects  the  best  elementary  text  book  on  the 
subject,  has  been  confirmed  by  my  experience  with  it  in  the  class- 
room." 


4  THE  AMERICAN  SCIENCE   SERIES. 

ZOOLOGY.     By  A.  S.  PACKARD,  Professor  in  Brown  Univer- 
sity. 
Advanced  Course.     Large  I2mo.     Pp.  719.     $3.00. 

Designed  to  be  used  either  in  the  recitation-room  or  in  the 
laboratory.  It  will  serve  as  a  guide  to  the  student  who,  with  a 
desire  to  get  at  first-hand  a  general  knowledge  of  the  structure 
of  leading  types  of  life,  examines  living  animals,  watches  their 
movements  and  habits,  and  finally  dissects  them.  He  is  pre- 
sented first  with  the  facts,  and  led  to  a  thorough  knowledge 
of  a  few  typical  forms,  then  taught  to  compare  these  with 
others,  and  finally  led  to  the  principles  or  inductions  growing 
out  of  the  facts. 

From  A.  E.  VERRILL,  Professor  of  Zoology  in  Yale  College  :  ' '  The 
general  treatment  of  the  subject  is  good,  and  the  descriptions  of 
structure  and  the  definitions  of  groups  are,  for  the  most  part,  clear, 
concise,  and  not  so  much  overburdened  by  technical  terms  as  in  sev- 
eral other  manuals  of  structural  zoology  now  in  use." 

Briefer  Course.     i2mo.     Pp.  334.     $1.40. 

The  distinctive  characteristic  of  this  book  is  its  use  of  the 
object  method.  The  author  would  have  the  pupils  first  examine 
and  roughly  dissect  a  fish,  in  order  to  attain  some  notion  of 
vertebrate  structure  as  a  basis  of  comparison.  Beginning  then 
with  the  lowest  forms,  he  leads  the  pupil  through  the  whole 
animal  kingdom  until  man  is  reached.  As  each  of  its  great 
divisions  comes  under  observation,  he  gives  detailed  instruc- 
tions for  dissecting  some  one  animal  as  a  type  of  the  class,  and 
bases  the  study  of  other  forms  on  the  knowledge  thus  obtained. 

From  HERBERT  OSBORN,  Professor  of  Zoology,  Iowa  Agricultural 
College :  "  I  can  gladly  recommend  it  to  any  one  desiring  a  work  of 
such  character.  While  I  strongly  insist  that  students  should  study 
animals  from  the  animals  themselves, — a  point  strongly  urged  by 
Prof.  Packard  in  his  preface, — I  also  recognize  the  necessity  of  a 
reliable  text-book  as  a  guide.  As  such  a  guide,  and  covering  the 
ground  it  does,  I  know  of  nothing  better  than  Packard's." 

From  D.  M.  FISK,  Professor  of  Natural  History,  Hillsdale  College  : 
"  The  'Briefer  Courses  '  of  Packard  and  Martin  have  been  adopted, 
and  for  these  reasons  :  I.  They  are  brief ;  the  lessened  mechanical 
labor  of  mastering  a  text  leaves  time  for  more  observation  and  for 
comparison  of  authorities.  2.  They  are  clear ;  the  work  of  cutting 
away  needless  nomenclature  has  been  done  with  skill.  3.  They  are 
authoritative ;  serious  students  can  have  confidence  in  even  brief  and 
dogmatic  statements,  knowing  they  come  from  a  master,  and  not  from 
a  mere  compiler.  4.  Thev  are  fresh  ;  fossils  are  good  in  their  places, 
but  a  fossil  text-book  in  science  is  a  fraud  on  youth." 


THE  AMERICAN   SCIENCE    SERIES.  5 

ZOOLOGY— Continued. 
Elementary  Course.     (In  press.} 

In  general  method  this  book  is  the  same  with  those  just  de- 
scribed, but,  being  meant  for  quite  young  pupils,  it  gives  more 
attention  to  the  higher  organisms,  and  to  such  particulars  as 
can  be  studied  with  the  naked  eye.  In  everything  the  aim  has 
been  to  make  clear  the  cardinal  principles  of  animal  life,  rather 
than  to  fill  the  pupil's  mind  with  a  mass  of  what  may  appear  to 
him  unrelated  facts. 

BOTANY.    By  CHARLES  E.  BESSEY,  Professor  in  the  Univer- 
sity of  Nebraska. 
Advanced  Course.     Large  12 mo.     Pp.  611.     $275. 

Aims  to  lead  the  student  to  obtain  at  first-hand  his  knowl- 
edge of  the  anatomy  and  physiology  of  plants.  Accordingly, 
the  presentation  of  matter  is  such  as  to  fit  the  book  for  con- 
stant use  in  the  laboratory,  the  text  supplying  the  outline  sketch 
which  the  student  is  to  fill  in  by  the  aid  of  scalpel  and  micro- 
scope. 

From  J.  C.  ARTHUR,  Editor  of  The  Botanical  Gazette:  "The  first 
botanical  text-book  issued  in  America  which  treats  the  most  important 
departments  of  the  science  with  anything  like  due  consideration. 
This  is  especially  true  in  reference  to  the  physiology  and  histology  of 
plants,  and  also  to  special  morphology.  Structural  Botany  and  clas- 
sification have  up  to  the  present  time  monopolized  the  field,  greatly 
retarding  the  diffusion  of  a  more  complete  knowledge  of  the  science." 

Briefer  Course.     I2mo.     Pp.292.     $1.35. 

A  guide  to  beginners.  Its  principles  are,  that  the  true  aim  of 
botanical  study  is  not  so  much  to  seek  the  family  and  proper 
names  of  specimens  as  to  ascertain  the  laws  of  plant  structure 
and  plant  life;  that  this  can  be  done  only  by  examining  and 
dissecting  the  plants  themselves  ;  and  that  it  is  best  to  confine 
the  attention  to  a  few  leading  types,  and  to  take  up  first  the 
simpler  and  more  easily  understood  forms,  and  afterwards  those 
whose  structure  and  functions  are  more  complex.  The  latest 
editions  of  the  work  contain  a  chapter  on  the  Gross  Anatomy 
of  Flowering  Plants. 

From  J.  T.  ROTHROCK,  Professor  in  the  University  of  Pennsylva- 
nia :  "  There  is  nothing  superficial  in  it,  nothing  needless  introduced, 
nothing  essential  left  out.  The  language  is  lucid  ;  and,  as  the  crown- 
ing merit  of  the  book,  the  author  has  introduced  throughout  the  vol- 
ume '  Practical  Studies,'  which  direct  the  student  in  his  effort  to  see 
for  himself  all  that  the  text -book  teaches." 


O  THE  AMERICAN  SCIENCE   SERIES. 

CHEMISTRY.     By  IRA  REMSEN,  Professor  in  the  Johns  Hop- 
kins University. 
Briefer  Course.     I2mo.     Pp.  387.     $1.40. 

An  introduction  to  the  study  of  chemistry,  following  the 
inductive  method.  To  avoid  overburdening  the  student's  mind, 
the  author  has  presented  a  smaller  number  of  facts  than  is 
usual  in  elementary  courses  in  chemistry,  but  he  has  at  the  same 
time  taken  pains  to  select  for  treatment  such  substances  and 
such  phenomena  as  seem  best  suited  to  give  an  insight  into  the 
nature  of  chemical  action.  In  other  words,  he  has  aimed  to 
make  the  book  scientific,  to  lay  stress  upon  the  relations  which 
exist  between  the  phenomena  considered,  and  not  to  present 
merely  a  mass  of  apparently  disconnected  facts.  Another 
feature  of  the  work  is  that  principles  and  laws  are  treated  be- 
fore the  theories  which  are  proposed  to  account  for  them. 

The  other  books  arranged  for  in  this  series  are  as  follows  : 

PHYSICS.     By  ARTHUR  WRIGHT,  Professor  in  Yale  College. 
{In  preparation.} 

CEOLOCY.     By  RAPHAEL  PUMPELLY,  late  Professor  in  Har- 
vard University.     (In  preparation.) 

PSYCHOLOGY.     By  WILLIAM  JAMES,  Professor   in  Harvard 
University.     (In  preparation} 

GOVERNMENT.     By  EDWIN  L.  GODKIN,  Editor  of  the  Nation, 
(In  preparation} 


THIS    BOOK    IS    DUE   ON    THE    LAST    DATE 
STAMPED  BELOW 


AN  INITIAL  FINE  OF  25  CENTS 

WILL  BE  ASSESSED  FOR  FAILURE  TO  RETURN  THIS  BOOK 
ON  THE  DATE  DUE.  THE  PENALTY  WILL  INCREASE  TO 
50  CENTS  ON  THE  FOURTH  DAY  AND  TO  $1.00  ON  THE 
SEVENTH  DAY  OVERDUE. 


Book  Slip-10m-8,'58(5916s4)458 


_  ,il  -IM-  ~        • 

Arthur,  J«G. 

Handbook  of  plant 
dissection* 


ArtU 


ur 


A7 


QK53 
AT 


168233 


. 

• 
. 


